I've stayed at the Doubletree in Mission Valley(
http://doubletree.hilton.com/en/dt/hotels/index.jhtml?ctyhocn=SDGO-DT) a couple of weeks ago and I can honestly say that I was very pleased with this hotel. Everything was in clean and new condition, the breakfast in the restaurant(while not expansive) was very delicious, and the Neutrogena toiletries were nice. The location was perfect because it's centrally located to many eateries, Sea World, and shopping. One thing I didn't like was that both the indoor and outdoor pool had a lot of chlorine and my eyes could not stand it. What I did upon check-in (but I don't know if I would recommend it) is that I parked in the mall overnight. You're not supposed to but since we checked in late, they said it was ok...plus, it was free!
So, would I stay there again? Absolutely! Let me know if this help any...