Costa Rica is in the rainy season right now, but it usually only rains for an hour or two each day and then the sun comes out. If you are looking for scenery, Costa Rica is hard to compare to. You may want to look into St. Lucia. I have 10 nights booked their next month, and it is as close to Tahiti as you can get. It also has great scenery (Volcano’s, Mountains, etc.). If your interested in St. Lucia, shoot me an email and I’ll send you some more information on a few resorts.
If you want sandy white beaches, then Aruba, Grand Caymen, Jaimaica, etc. are better choices. If you want night life, Aruba is hard to beat. It all depends on what you are looking for.