I've not cruised before, but my girlfriend has, and my understanding is that last-minute is when you can get the best deals. Not to mention you are more aware of whether or not any storms are coming.
I also am not a "lay on the beach" or "hangout at the pool bar" type. I want to be doing something (fun).
If you are interested in a really cool trip. The best I've been on was with my Ex & our 2 kids. We went to Belize, spending the first half of the week at a resort in the rain forest, and the 2nd half of the week at a more traditional beach resort. The beach resort was nice, but really it was just a chance to relax after all of the adventure at the rain forest resort. This place is small, 24 rooms, each room is a separate tree-house. Only power to the rooms was to run the ceiling fan. Had a nice outdoor shower (also an indoor one). One entire side was 100% screened in (no wall) overlooking the jungle & river below. They had a covered area where everyone met for dinner (also had breakfast there), great food, and they would walk from table to table with a list of 8-10 activities and asked you to pick which one you wanted to do the next day. Some that we didn't do included: swimming w/ the sharks, cave tubing, chocolate making tour, zoo trip. What we went with were: zip lining, waterfall rappelling, caving, and sink hole rappel. These would usually last from like 8 until 1 or 2, then when you got back (exhausted) everyone would go to the pool, and talk with the other guests about what they did giving you ideas on what you did or didn't want to do the next day. Oh, and the local made drinks are free there too, but you pay for non-domestic.
- the zip lining was ok, we did better the year before in Colorado, and a couple years later in Costa Rica
- the waterfall rappelling was also ok, but we did better a couple years later in Costa Rica
- the caving was great. You would follow this stream in the cave, going under water at one point, and then when you would get to a waterfall, they would put safety gear on you and you would climb up it, and then go on to the next waterfall. I think there were 5 or 6 total. At the end you swam in this small pool sized area, then it was time to leave. Once you got to the edge of each waterfall, you had to jump off (into this dark hole); the highest of which was probably about 15'-20'.
- the sink hole rappel was the most scared I've been in my life (more than the one time tandem skydive), so very exciting. It started with an hour-long hike to the top of this hill, that put you on the outside of an enormous sinkhole, which was several football fields big, and 300' deep. They then put your rappelling gear on you, showed you the safety (the backup to your gear, and the backup to the backup). And then you step-off the edge and rappel down 300'.
The place is called Ian Anderson's Caves Branch Resort. There are some cool Youtube videos guests have taken showing some of the stuff you do there.