The drive from LA to SD takes about 2 hours in no traffic. Sometimes you can make it a little faster but I would estimate 2 hours.

The Sheraton in Carlsbad is awesome for legoland. The property itself is also quite nice and spread out.

The SLS is great but there really isn't any room for a child to roam around, etc. I used to always see Khloe Kardasian walking around over there but maybe no more since she moved to Dallas.

The St. Regis Monarch Beach is a great hotel and probably the best SPG property in Southern California. It's also great for kids because there is a lot of space to walk around, etc. They even have a small kiddie pool. The golf cart to go to the beach is a bit of a pain (sometimes it fills up and you have to wait) and the ride is always longer than I think it is. The area is great but is a bit far if you want to go to Disneyland, etc. It's really meant to be a resort where you check in and don't leave.

Sorry to say but the Sheraton Delfina is probably one of your best options for price, location, etc. You can get over to 3rd st promenade, drive over to hollywood, etc.

The airport properties are all dumps but convenient if you have a morning flight.

The Westin Bonaventure is huge but is also a dump. Lots of people stay there because the rates are usually low but it's really a dated property and downtown LA is pretty boring on weekends.