Okay - I’ll jump in here since I’ve lived in San Diego for a long time, have been most other places (and lived in other places, and love it here. I’ve been to Florida multiple times including for a vacation (all over Fla), have been to Santa Fe, and most other places. If I was from elsewhere I’d choose San Diego due to the wide variety of things to do, the weather, the varied terrain, etc.
Santa Fe is okay for a 1 or 2 day visit but unless you plan to ski nearby or hike a lot in the area you may run out of things to do. If you plan to hike keep in mind the winter weather there can make for a cold and possibly wet hike.
The weather in San Diego is usually great year round including Christmas time. Note the key word ‘usually’ because it’s possible to get a storm, have some rain, etc. but it’s usually minimal compared to anyplace else in the country. I often head down to the auto show at the San Diego convention center which is always right around end Dec/beginning of Jan and I almost always revel in how unbelievably nice it is out. Walking around that area (downtownish along the waterfront) always makes me feel like I’m on vacation.
I really like La Jolla as well and walking around LJ also always makes me feel like I’m on vacation. I was there about a week ago and it was great.
But I also will head to Coronado every now and then and of course, feel like I’m on vacation while I’m there.
- Where to stay: There are lots of choices and it depends on what you want and your budget. If it were me coming here for vacation I'd want to stay near the beach/waterfront, preferably within a short walking distance from the beach. 'The beach' could be many places including Coronado, La Jolla, downtown waterfront, or a bit further north in Del Mar or Carlsbad, for example. I would 'not' want to stay in Mission Valley - i.e. 'Hotel Circle, or 'Old Town' but only because I'd rather be on the waterfront. There are some hotels around 'Mission Bay' that are nice that are on the water although it's a smaller bay type of water area.
The reason I state the above is because the waterfront/beach area will make you definitely feel like you’re on vacation. They also provide ready access to nice walks, kayaking, sailing (including little sailboats), and other water activities.
I’d probably choose either La Jolla, Coronado, or possibly one of the hotels right along the downtown waterfront (there are some big ones there - Hyatt, Sheraton, etc. and some other options).
In Coronado the big hotel is the Hotel Del Coronado but it’s also expensive. Check into the ‘Glorietta Bay Inn’ which is right across the street from the Hotel Del but less expensive. If you stay in the mansion house it’ll be a unique experience. Check it out on the internet.
There are a number of hotels right in the La Jolla Cove area of La Jolla. That’s a great location.
- Restaurants: They're all over the place. Be sure to try some Mexican food places since there are lots of them in the San Diego area. 'Old Town' has a number of decent ones but again, they're all over.
There are fancy and expensive restaurants in La Jolla and a previous poster mentioned some but you can also grab some food, for example at Burger Lounge (really good burgers) and walk to the La Jolla Cove area and eat it there.
By downtown San Diego is the ‘Gaslamp District’ which has a number of restaurants but there are also many restaurants all along the waterfront including in ‘Seaport Village’ (shopping) which is all walkable from that waterfront area.
- Things to do: -- Go to the beach. It's free, fun, and interesting. I'm not a 'lay there in one spot person' but I go there frequently and walk - often for miles. If you're walking on the beach at La Jolla Shores down by the couple of hotels that fron the beach there, look for the leopard sharks you might see in the water there. They're harmless but interesting.
– Water things - snorkeling, surfing, boogie boarding, body surfing (would need a wetsuit in the winter), sailing, kayaking, San Diego bay boat tour, dinner cruise, sailing tour (your family on a sailboat piloted by someone who does it for a living), etc.
– Walk the downtown waterfront, perhaps go on the old ships and sub at the maritime museum there.
– Visit the USS Midway aircraft carrier - on the waterfront downtown.
– Go to La Jolla Cove (drive if you’re staying elsewhere) and walk around it and watch the sea lions and seals that are always there.
– Balboa Park - zoo, aerospace museum, other museums.
– Sea World, Safari Park (by Escondido - a northern suburb).
– Rent bikes in Coronado and bike around.
– Lots of places to hike and bike in the San Diego area.
– Many other things already mentioned by others.
– Further afield -
— Julian - an old gold mining and stagecoach stop town in the mountians east of San Diego. Something different and you might even get to see snow (I realize - you’re probably trying to escape snow)!
— Borrego Springs Desert State Park. This is in the desert east of San Diego and east of Julian. There are some great desert hikes there including some near the visitor center.
— Palomar Mountain 200" telescope - was once the largest in the country. This’ll be something different and again you might see snow.
— Temecula (north of San Diego) for wineries.
— Disneyland is about 1.5 to 2 hours away. Universal Studios is maybe a half hour or so further.
— Catalina Island
— Anything else in the Orange County or LA area.
- Getting around: Having a rental car means you can get around easily and could head between all the places mentioned.
The downtownish area of San Diego has a trolley/light rail system that could be used if you don’t have a car and are in that area.
If you’re staying downtown/waterfront or Coronado you could take a ferry between Coronado and downtown San Diego. It’s not that expensive and is quick (short distance) but if a family did it several times per day for multiple days it’d add up.
Getting from Coronado to downtown by car is actually quick and easy - just head over the Coronado bridge and you’re there (either downtown or Coronado).
I didn’t cover everything but as you can see there’s a lot to do and importantly ‘you’ll feel like you’re on vacation’.