Well, if you're looking for casino/hotels, they are going to be a good 40+ miles from the sights and sounds of SD. So if you're looking to sight/see our beautiful city, you're better off staying in the general SD area and drive to the casinos if you have a car. And even if you don't, the casinos have plenty of shuttles that will pick you up or drop you off around your hotel area.
I don't know if you're traveling with kids or not, so I don't know whether or not you'd want to visit Legoland, the zoo, Sea World etc. You don't have to be a kid to visit Sea World or the zoo or plenty of other attractions. You can take a harbor cruise or even take a Hornblower dinner cruise which is always very nice. You didn't mention what time of the year you're coming out here. Hopefully it's not during the summer season when all attractions get filled up fast. We went to Sea World during the summer when Faye's daughters family came to visit and I swore I'd never do it again. In order to get to see a show for example, you'd have to get in line as soon as the previous show was starting to be let in, and in the summer, even though it really doesn't get that hot, you really start to roast when waiting in line in the sun with no shade. By the way, if you do go to Sea World, check into the many places that offer discounts for your entry. Sea World has a promotion going on now that if you buy a ticket, you can return to SW as many times as you want for the next year.
If it were me, I'd try and stay in Mission Bay where they have many tourist hotels. You'd be right on the Bay with the ocean not too far away. You could take advantage of the many water sports that the Bay area offer either through your hotel or the other outlets that offer what you'd like to do. Water skiing, para sailing, kayaking, paddle boarding and even surfing. Bicycle rentals are offered almost every other block. At the end of Mission Ave. there is Belmont Park which has some rides like a roller coaster, merry go round and even a water park where you can surf without ever having to go into the ocean.
If you're coming in the next couple of months, don't worry about jackets or rain gear as the weather is really very nice this time of year. Today it was an unusually high 90 degrees where I live, but down by the ocean it probably won't reach a high of 80 degrees and normally in the mid 70's. Water temps can be a little low this time of year, but the Bay will probably be a little warmer. And as they say, you can get "used" to it in a couple of minutes.
