My family and I stayed here for 10 days and used it as a base for various Southern California trips. Even though it is a luxury resort, it is a great place for families. The staff treats you very well and seem comfortable around kids and dealing with families with kids. There are two pools -- one for adults and one for families which is a very nice touch. The park suite was perfect, large, and had everything a small family could need. Love the Illy coffee maker.
The valets are professional and will help you with just about anything you need. Everyone calls you by your name. The pool staff was inconsistent at times, but generally also very accommodating. The swim-in movie night is a nice touch. Our kids loved it.
We originally had a hiccup with check-in because our room was promised but not ready. We ended up waiting in the hotel and the lobby for quite awhile. Mostly, I think this was due to poor communication by the desk clerk who was wearing a "trainee" badge. I think she made promises that were just not reasonable as to when the room would be ready. Nevertheless, once the room was ready, the manager stepped in and offered to waive our parking fee as a means of compensating us for our trouble. Very generous.
A couple of tips. Vivace (which is excellent) has a dress code and when you make reservations the concierge should tell you about that. I had to run back up to the room to put on long pants. The Beach Butler is a great benefit and covered by the resort fee. If you go to the beach or are planning on it, get on the reservation list for the Beach Butler early the spots fill up fast and there aren't that many of them. If you don't get on the Beach Butler list, the valets will still give you towels and chairs for the beach if you want to drive yourself. Take advantage of the shuttle to the tennis center. It's beautiful and for those who play tennis, Steve is a great teaching pro.
In short, I felt really lucky to have found the Park Hyatt Aviara and would recommend it to anyone staying in the San Diego area.