Costa Rica is heaven for mongers. Women come from all over to work there and there is tons of variety and options. You can go to massage parlors, brothels, pickup bars, and of course use agencies/independent escort sites. Escort prices will be as high or higher than TJ, but there are a lot more lower-priced options. There's also tons to do, and is a great vacation destination. No one wonders if you are going to Costa Rica for the hookers, like if you go to Thailand or Tijuana
Dominican Republic is a great tourist destination as well, but the variety of women is not there. You really have to like dark-skinned beauties. Yes, there's some variety but not like in Costa Rica. It's also a lot cheaper than CR. I have to say that I've only ever been to the north coast of DR (Cabarete, Sosua, Puerto Plata). I have no experience with Punta Cana or Santo Domingo.
Tijuana is not much of a tourist destination -- although it is easy to pop back to San Diego for things to do. I tend to tell people I'm going to SD rather than TJ, lol. Lots of options in TJ, and there is variety but not as much as Costa Rica. Prices will be higher than either CR (mostly) or DR.
As far as travel, it is worthwhile for me to go to TJ for just a few days, as there are nonstop flights from KC. So I can fly in on Saturday morning and fly out on Tuesday evening and have play time all four days. I really can't do that for CR or DR (if I lived on the east coast, DR would be super convenient, I guess).