Practice on the instructors especially if he has several models try them all out and find the one that you are most comfortable in. Or if you even enjoy it enough to want to buy one. You also will need to take into account what type of water you intend on using it on ie white-water, ocean, or calm lakes and streams for camping or touring.

Here are some things to factor in; do you want to ride a sit on top or a sit inside kayak? You said you're going to be up in Alaska so I'm guessing a sit inside. Will the water you're paddling on be isolated in strait, a river or open ocean? If it's isolated and there's not much of a chance of you needing a forward watertight compartment, this type might assist in compensating for your height. There are plenty of ocean going kayaks that are long enough to give you plenty of leg room and not give up the forward stowage hatch. I know a lot of the people I talk to would like to go paddling but are afraid that if they have a spray skirt on and they capsize, that they will be stuck in the boat. My boat opening is fairly sizeable and I can tell you it's more difficult to stay in than to fall out. If this is a concern for you, you should consider a larger size opening. A spray skirt is a must though. bad Weather comes up in hurry and with no warning sometimes. I guess the last thing to consider is to have a rudder, skeg or nothing at all. I've found I have the best luck with a skeg to help counter weather-cocking, so you could say I'm in the Skeg Camp. My concern is the rudder being damaged in a surf launch or landing. There are others who will completely disagree with me and always prefer a rudder. I think a simple adjustment of the paddle and a slight lean works just fine for turning. Either way, bring a waterproof case for your digital camera as you'll want to show everyone where you were and to make them jealous!