-- Last Updated: Dec-19-12 3:52 PM EST --
Here is the most important thing you said - "We want to purchase kayaks that we can grow into."
You don't know enough to know what that means in a boat until you have some butt time. I am talking fit, tracking versus maneuverability, all kinds of things that are too academic for you guys right now.
I just reread and caught that the place you went to look at kayaks has pool sessions. Take advantage of them. The very best way to find out what features matter to you in a kayak is to actually try and execute things like rescues, on-water recoveries and braces. The first time you find a wet kayak sliding out of your hands, for example, you quickly understand the value of perimeter lines.
Also, you are making the common newbie mistake of underestimating the skills and boat features that are apt for being serious about class III whitewater. It requires some of the skills in which you expressed a lack of interest, like rolling. And the boat that does a great job of supporting advancement in flat water skills as well as having a nice hull for longer days tripping is not the same boat that will support advancement in whitewater.
I suggest that you focus first on a good flat water boat - which is not truly flat water by the way. It really just means there is not a strong enough current to drag you under a log, "flat water" can be plenty not-flat. WW boats are cheap and easily obtained used once you have some idea what you are doing.
You also probably should rethink buying new. If you really want boats to grow into, and thinking of the gear and clothing you'll want for the northeast, demo and used boats will get you some nice choices at the price point you mention. There are plenty of ways to spend money to support your local outfitter when you are first starting out.