Good luck with TACA -- I've heard some wild stories. I find great fares on the American Airlines on line reservation system. $445 RT from SF to Belize City.
Yes, there are lots of places that will set up packages for you, if that's what you want.
I used these people for my 1st two trips and was very happy http://www.tradewindsparadisevillas.com/index.html
As you will see, there has been a lot of posts about Paradise Village/Tradewinds, etc. All the same place. Highly recommended.
Galeen: I just saw this and we are neighbors - Concord is even hootter than Martinez at night.