Wind!!! it seems like the wind is always blowing. You need a rod with enough power to cast into the wind. that is why most saltwater flyfishers use the stiff graffite rods. I would recomend the 8 weight. If you fish a lot in the backs of creeks or other protected waters a 7 could be fun.
Next is fly fishing is really a sight fishing situation. If you know where you can see tailing reds like I used to fish in the mosquito lagoon that is where you need to fish. Blind casting with a fly rod will surely wear you out. by the way if you know where those reds are

As to the length of the rod. One of mine is 8.5' and the other is 9.5' and I like the longer rod unless it is a tight quarters. I used it for snook fishing around the mangroves. I wade fish a lot, or used to till I saw all the sharks off econfina. and that extra length sure helps when you are waist deep. I think it would also help sitting in a kyack.
St Croix has a line of reasonably priced fly rods. Nothing will turn you off quicker than poor equipment. As to a reel there are several reasonably priced reels and a good one will last forever. I would reccomend a large arbor reel. Reds and Trout won't really test your drag but i was in Panama City this summer and those bonita will really put on a show.
Like Tom says fly fishing is for people who have caught too many fish. I always have a fly rod and if it is one of those rare days that the fish are biting everything you throw at them and the wind is not blowing Its time to break out the fly rod. And if you catch a fish on a flyrod with a fly that you tied that is satisaction.