@mathmom, please do!!!
@mathmom, I just saw that I had posted in your thread. Forgot all about it, lol. Then again, I have a big post count, so easy to lose track. 
We stayed at Half Moon Bay (which is north of Carmel) about 5 years ago when my H attended a conference there. After the conference, we did some exploring in the area and went to a great beach with amazing cliffs that was beautiful (Pescadaro Beach). Also, there’s a fun restaurant–Duarte’s Tavern–in the town of Pescadaro, which is known for its artichoke soup, crab cioppino, and pies. It’s not fine dining, but the food is very good. NPR did a story on it a while back. http://www.npr.org/templates/story/story.php?storyId=
What’s the ocean water temperature in August?
@Igloo, according to this link, not exactly warm. That’s okay by me; I’m not going for warm weather. I WANT cool temps at night. We are sick and effing tired of 108 degree days in Texas in August!
Absolutely loved Pt Lobos State Park.
We ate here and the setting was lovely.
I second the suggestions above about Pacific Grove. For a local meal that won’t break the bank but is delicious, Peppers Mexicali Cafe is excellent. It is on Forest Ave. in Pacific Grove.
Also, Point Lobos is stunningly beautiful.
Nepenthe is inaccessible right now, unfortunately. I second the recommendation for Duartes in Pescadero (try the pie). Pescadero is a tiny little town that used to be quiet, but now is quite the tourist draw on weekends. If you go to Duartes, stop in across the street at Arcangeli to get some artichoke bread.
I love the Monterey Bay Aquarium.
If you drive up the coast, Gayle’s Bakery and Rosticerria in Aptos is sensational. Sometimes I ride my bike over for lunch. It’s 45 miles each way, over the mountain. Worth it.
Mr. Fang and I spent a couple of days in Carmel in January. We liked the Flying Fish restaurant: http://flyingfishgrill.com/
Even when we lived in Los Angeles I thought the water was freezing all summer long. (Used to East Coast water temperatures - thank you Gulf Stream!)
Back decades ago, we golfed at Pebble Beach with our law firm, as a bonding experience. Had never before or since golfed in down jackets and thermal clothing. It was freezing, windy, very memorable in December, if there are golfers amongst you and anyone Is up for high green fees and you can get a tee time.
Hearst Castle is so large that there are a number of different tours so you could visit it more than once and see something different.
Reserve (purchase) your tickets online up to 56 days in advance.
The nightime tour ($36) is more than the daytime tours ($25).
17 Mile Drive can be torture if it is busy. Like a voluntary traffic jam, and the Lone Cypress has a stone wall built around it so not very untouched-looking. I would skip it in favor of more time at Point Lobos where you are free to walk around that beautiful place.
Some random ideas for your stay -
Start reading the weekly local paper, The Pinecone, on line before you get there. It will give you a good idea of local events.
The Carmel area has a number of wine tasting options. There are a bunch of tasting rooms right in town. You can experience lots of Monterey County wines without having to worry about driving afterwards!
About 20 minutes away are the wineries in Carmel Valley. Some have tasting rooms in Carmel Valley Village or other locations along Carmel Valley Road, and others offer vineyard tasting rooms.
About an hour’s drive from Carmel (over the hill towards Salinas) is the Santa Lucia Highlands wine growing region. River Road houses a number of vineyards with tasting rooms. Two of my favorites are Wrath and Hahn. They both have nice wines to taste and lovely grounds. Bring a picnic if you want to have a meal during your visit. The area really doesn’t have any restaurants.
Although Highway 1 is closed before Big Sur proper, Big Sur River Inn is still accessible. The drive to get there is very scenic, and the Inn has a nice restaurant right on the river. It would make a nice day trip.
Another entertainment venue within walking distance is Sunset Center.
There are several weekly farmers markets in the area. The local produce is wonderful. Earthbound Farm has a farmstand/cafe/garden in Carmel Valley that is open every day, offering lots of tasty, local, organic foods.
If you like car races, Laguna Seca Raceway is just a short drive.
A word of caution about Concours week - traffic and crowds are an issue. Leave your car at home, and walk to the shuttle stop in Carmel if you will be going to any of the Pebble Beach events. If you can avoid driving during daylight hours during that week, do so.
Go to the Lodge at Pebble Beach (not during Concours week!) to enjoy a sunset cocktail at The Bench. It is a bar and restaurant overlooking the famous 18th green and Stillwater Cove. Get there early for an outdoor table.
Salumeria Luca has the most delicious selection of Italian meats and cheeses. A perfect place to get food for a beach picnic.
The rules for beach fires have changed recently. Wood fires are now only allowed in the city-provided fire pits. Fire hours are four to ten pm. This system is new, so I’m not sure how early you have to arrive to stake out your territory.
Dogs are allowed on the beach without a leash. Carmel is a very dog-friendly town, with many businesses catering to people who bring their pets along while they shop and dine.
The public library is surprisingly good for such a small town. They will issue you a visitor’s card for a nominal fee.
That’s enough rambling - lol. I hope you enjoy your stay!
Hearst Castle is currently 155 driving miles from Carmel. It’s rather like going to Seattle and saying you’ll make a day trip to Portland. You can go, but it’s a long way.
If I were there I would go to Point Lobos every single day. It is glorious. Because of the mud slide it is impossible to get to the Big Sur Bakery and Restaurant but I have read that they are having pop up events. Their food is very good.
You can make a trip to Hearst Castle and stay overnight and visit the wineries in Paso Robles.
If I were spending a month in Carmel, I think a visit to the Hearst Castle would be a perfectly reasonable thing to visit. (Maybe as an overnight.) We are only going to be in the area for a few days, so definitely on for us. It was the big regret of my honeymoon that we drove right by it. In any event having just seen two mansions in Newport, RI, I’ve seen enough of the gilded age for a while.
If going to Heast Castle, I’d definitely try to stay at a nicer place than we did. It was a 2 or 3* and really got our allergies activated 
It is a cool place to visit if you’re trying to find memorable things to do and see in your month.
If you are a Steinbeck fan, there are a number of literary locations in Monterey. Also locations related to Robert Louis Stevenson.