I used to get annoyed when someone would answer a question such as the OP with "do a search" rather than answering the question. But in this case, I have to say I would do the same thing.

First of all, there are numerous threads about hotels at LAX and San Diego proper as well as the north San Diego county. Second, hotels are a much more personal decision than, say, airlines because they are so very different from each other in both cost and style.

Many of the threads here have detailed discussions about the hotels that would allow the OP to make that personal decision. These threads are in various places -
1) The Los Angeles forum
2) This forum - the California forum
3) Individual hotel brand forums - Marriott, Hilton, Starwood, etc.

TO repeat all of this information would really be impossible. So my suggestion is that you stay on FT, go to each of these Forums, click on Search, and enter keywords such as airport hotel, San Diego hotel, Legoland, Carlsbad, etc. I think you will find more than enough information to fit people's experiences into your own personal preferences.