Clarity-
Just my experience. My first trip to Jamaica was an impromptu trip from Florida in 1975. I was there with a friend, and when she left I decided (on some advice from a couple that had just returned) to go to Negril. I had one hard sided suitcase and an old guitar. In those days, you either bought a ticket for 6 weeks or less, or more than six weeks. I bought the cheaper one thinking "I won't stay anywhere near that long". Almost three months later I showed up at the airport with my 6 week ticket. After it was determined that I actually had NO MORE MONEY they just told me "Get on di plane mon". Since I've started going back with my wife over the last 7 or 8 years I've been back 16 or 17 times. Everyone with just a carry on. My wife also is just carry on (besides her huge purse ;>).We go for between 10 and 12 days each time. We have never had a problem running out of anything (except maybe money ;>). We've learned over the course of time that we can get many things in Jamaica as cheap or cheaper than in the states. Shampoo, creme, conditioner etc.. We also leave anything not used behind for the staff. Also, I've been on many types of planes from many airlines (USAir, Delta United, American) and have NEVER had a problem with my carry on fitting either in overhead storage or under the seat. Whatever you decide I know you will have a great trip. As I'll be in Negril at the same time (4-17 - 4-27) hopefully I'll run into you and Marcus at the beach (or canoe, or the Jungle, or wherever ;>). I'll be the thin guy with the chinese tattoo on his back.
Respect
Kirt