I stayed there back in December for 3 nights for a training class I had in SAN. Overall the hotel is decent. The front desk made no mention of HH Diamond, and worst of all...no cookie??? I had just gotten off a CLT-EWR-SAN CO flight and didn't feel like pushing it.
The room was decent - I was on one of the higher floors and my room faced toward the city. Pretty decent view and a great breeze. Nice little side chair with ottoman for relaxing.
The location is not great, but it is not too far of a walk to the gaslamp district. There are several other hilton brand hotels in the gaslamp, which would be a better choice, but my training class was in the DT.
As far as food, I would recommend walking around little Italy if you want something quick. But I would imagine, the steak salad is a fan favorite around FT community (not quite bird food, but still healthy) - can I suggest a the steak salad at the Currant? It is in the bottom of the Sofia hotel at Broadway and Front. It is the best steak salad I have ever had.
Cheers