Everyone eats out a lot more than I do so no restaurant suggestions. A walk along La Jolla Cove or Torrey Pines is lovely. It is a very strange hot and muggy right now. Should be back to drier weather by Friday. 76% humidity is not the norm
@conmama I second the recommendations for visiting Balboa Park and Torrey Pines State reserve. I’d also suggest a trip over to Coronado – the Hotel Del Coronado is worth a visit (it’s a beautiful, historic beachfront hotel where “Some Like it Hot” was filmed).
If you like theater, there’s a new musical with the music of Huey Lewis at the Old Globe (in Balboa Park) that’s a lot of fun.
As a general rule, I would avoid trying to get from one place to another around rush hour (between 4 and 7) on weekdays; you’ll spend a lot of time stuck in traffic.
Lunch at Georges in La Jolla would be nice – the top level patio has the best view (and is more casual – and less expensive – than the fine dining restaurant on the first level). The view from Del Mar Plaza (where Il Fornaio is indeed lovely; for dinner, there’s also Jakes or Poseidon that are directly on the beach in Del Mar).
The wouldn’t bother with Gaslamp restaurants – as others have said, they mostly cater to tourists and conventioneers. In my opinion, there’s nothing too special to see or do the Gaslamp.
As for the weather, bear in mind that muggy is relative. It’s generally pretty temperate, so the mugginess is not too uncomfortable (just not as enjoyable as the more typical, sunny blue sky.) As for clothing, you never need more than a light jacket in the evenings.
If you like beer, you’re in heaven 
Muggy today because of the tropical storm, but we didn’t get rain in north county.
Bring a light sweater, especially in case of fog.
Head out to Old Town for touristy/ historic walk.
I also recommend Little Italy for food.
Agree with @marvin100!! San Diego craft beer is the best. If you do make it over to Point Loma to Liberty Station as suggested upthread (Liberty Station is the old Naval Training Center…I’ve attended a boot camp graduation there before) go to Stone Brewing, it’s one of the largest craft beer breweries in the country. Excellent food and of course must sample their beer! https://www.stonebrewing.com/visit/bistros/liberty-station
Point Loma is also the site of Cabrillo National Monument (1542 the year Juan Cabrillo landed in San Diego Bay); the Old Point Loma Lighthouse is also located here.
Since your husband is interested in the beach, he might like Ocean Beach with the longest concrete pier on the west coast and tons of surfers. It’s a old eclectic hippie area that’s slowly gentrifying but very Californian. One of my favorite lunches is to have tacos at South Beach Bar & Grill on the upper deck overlooking the pier and watching the surfers. I also love walking the pier and if you want a different experience, you can have lunch at the WOW (Walk on Water) Cafe most of the way out on the pier. Not particularity great food but you can not beat the view.
If you do go to OB, drive on down to the end of the peninsula to Cabrillo National Monument and absolutely stupendous views of the ocean, bay, and city. But not if it’s foggy/hazy.
Coronado and Torrey Pines are indeed top tourist choices and well worth seeing. Maybe you’d like to extend your trip? 
The humidity does make for better sunsets.
Stone’s great (but their beers are available everywhere). Other top-flight breweries in SD:
Modern Times
North Park
Pure Project
Societe
Alesmith
Mikkeller
Ballast Point
(there are so many more worth mentioning, but these are my favorites)
I used to travel to SD for work and ate out often so I can share a few favorites. For view dining I don’t think you can beat Coasterra - fancified mexican right on the bay. I would take “visitors” there and everyone loved it. In Little Italy I enjoyed Herb & Wood (but it and all its sister restaurants are spendy) and I loved Ironside Seafood. Don’t stand in line at the family italian place that’s been there forever - the line is far more memorable than the food and the wine is terrible. One of my favorite places to eat dinner was a New Zealand themed bar called Queenstown Public House. Their lamb kebabs with hummos is worth the trip. I would steer entirely clear of Gaslight for food - it’s mostly mediocre food aimed at drunk tourists.
Heck - missed a typo. Gaslamp. Sorry.
Had to add - I didn’t make it out to Pacific Beach often but I did like Luce Bar and Kitchen which is closer than downtown - just over the freeway from Mission Bay. Small, relaxed spot but easy to get a seat (many restaurants in the area have communal tables) and the food / wine was fab.
Wow! So much great info and I’d love to do all of this, but will have to save some for next time. The first time we went we took the Old Town Trolley hoho bus and did get to see a nice snapshot of the city, hopping off at Gaslamp, and coming back that night to eat in Little Italy, although I wouldn’t say we toured around it too much.
We are going to the Hotel Del one night for dinner. Unfortunately we are only there 3 nights so won’t have time to do a lot. We are ubering everywhere. DH surfs so that’s why we picked PB, I like the area, but I agree it draws a younger 30 and under crowd. Almost all the shops really cater to them, that’s ok.
So, 1) one night JRDN and waterbar. 2) Hotel Del Coronado and 3) Somewhere in Little Italy or Gaskamp, or the hotel in the bay might be pretty someone mentioned. Need to research more.
I’d like to try World Famous for breakfast. As you can tell, I like to plan. I hate getting places and thinking “where do we go”
I’ll definitely be asking you all Thursday about the weather again!
@CaMom13 , I made reservations at Coasterra through opentable this morning. That’s exactly what I’m looking for the last night. Bummer they are only open until 9. Does that mean they shoo everyone out at 9?
Since your husband likes to surf you might consider staying in La Jolla Shores on a future trip. Local surfers love Scripps and Blacks Beach to the north.
I agree to stay out of the Gaslamp. Not much there except tourists.
For breakfast I recommend Beach Grass Cafe located on the coast in Solana Beach. Try their delicious blue corn pancakes.
Agreed on the terrace at South Beach in Ocean Beach. I anticipate their many sorts of fish tacos more than any of the other wonderful food in San Diego. S lives there post grad school, and scopes out the restaurant scene. Hash House for breakfast is mind boggling and delicious, though often a wait.
I always take the locals recommendations for attire with a grain of salt. I comfortably enjoyed the pool at the Hotel Del even though the pool attendant was wearing a hat, a coat, and gloves.
^Ha, like the time the lifeguards at our Disney World hotel were wearing white parkas and my kids stayed in the unheated pool for hours!
Never been to World Famous for breakfast, only happy hour/dinner. Nothing too special besides the location by the beach.
Many restaurant kitchens stop serving at 9pm…they won’t necessarily kick you out, but they won’t seat anyone new. Not too much in the way of late night dining in San Diego, I’m afraid.
Haven’t been to Coasterra yet, but the C-Level lounge at Island Prime (right next door) has a great happy hour and the views are indeed spectacular there.
Another thing you might want to do while you’'re in area around the Pacific Beach and La Jolla is to go to the top of Mount Soledad (it’s the peak between Pacific Beach and La Jolla). Great views from up there (although I’m not a big fan of the memorial itself, which has long been a source of controversy). Speaking of long sources of controversy, while in La Jolla, you may want to go to the Children’s Pool (south of the cove) and see (but please don’t disturb) the harbor seals. And, if you’re really ambitious, you can rent a kayak or snorkel around the caves just north of the cove. And now that I think about it, Brockton Villa might be a nice breakfast/brunch place.
Brockton Villa used to be a nice place to eat, but now with the sea lions above the cove it doesn’t smell too good. Maybe if you eat inside it is not so bad!
One of my favorite things to do in SD is have lunch on the Ocean Terrace patio at Georges on the Cove in La Jolla. After your meal, you can walk along the ocean and watch dozens and dozens of sea lions basking in the SoCal sun.
Our favorite dessert place is Extraordinary Desserts which has 2 locations: Balboa Park and Near Little Italy. Many good brunch places: Great Maple, Breakfast Republic, and Snooze- all which can have long waits. Balboa Park has many gardens, most are free admission- my favorite is the cactus garden which has some unusual cacti.