Best Rod Wt. for Tropical Fishing/Location

Need some advice, the moment I 've only fished the salt casting for coho out of boats for coho on Van. Is. but was thinking about doing some tropical flats fishing in the near future. I own a Sage RPLXi2-8 wt. and a Sage RPLXi- 9wt. I rarely use the 9 wt. for salt because I prefer the 8 Wt. and don't use it in the fresh either because I would rather use my spey setup. I've got a buyer for the 9Wt.

So here's my I being too hasty bout selling it? Would I be better off keeping it for salt water flats fishing or is the 8 Wt. the better way to go?

My other question centers around location. My wife and I are planning a Carribean cruise in March. There are lots of choices as to what islands to hit. I'd like to be able to beetle off and do some fishing if where would you suggest? Cheers!