About tiki bars- the best one is False Idol in Little Italy, which is ~ 5-10 minutes from the Gaslamp by car. It is located inside Craft & Commerce which is a casual restaurant that I recommend.
The Grass Skirt is another option, I like the cocktails a little less but the food is quite good. This one is located in Pacific Beach, about 20 minutes from the Gaslamp. Entrance is through the adjacent restaurant Good Time Poke.
Bali Hai is an original tiki bar in Point Loma that has been around since the 1950s; it has a great view and is a beautiful restaurant and bar, however the cocktails leave to be desired. Still worth a visit if you are a tiki fan.
Fairweather in the East Village (adjacent to the Gaslamp) used to be another option, however it recently changed hands and I no longer recommend it.
There is some info in this thread too:
