I wouldn't limit yourself to just what your local dealer carries. Avon is another major brand I would take a look at. I believe their US service center (might be just an east coast center) is in North Carolina. In any case, research goes a long ways in figuring out what's available, what you need/want, and what you can do without.
Tiller vs remote steering will save you a little money, but probably not all that much if you're buying new. Tiller will, however, gain you a substantial amount of deck space, at the cost of a bit of convenience (my opinion, after having moved from a 14' tiller steered SIB to an 18' center console RIB.) The console gives you a good place to store stuff, and mount electronics and antennae and such, should you need to do so (though some folks in tiller steered boats have come up with some, uh, creative ways around that problem.)
You say a family of 4; is this 2 adults, 2 smallish kids? Or are you looking at 4 adults (or 4 adult-sized people, anyway)? A 14 will be OK, if a little cramped for 4 adults. Longer is generally better, up to the point where you can't store it (factor in the trailer, too, when you're figuring out storage.) Remember the kids (if any) are going to grow, and will invariably want to take friends out.
I would suggest getting an engine that is at or near the max HP for the boat you get. Invariably, loads get heavier the more you use the boat.
I prefer hypalon over PVC (my personal preference), but that is opening a can of worms (the debate on material has been hashed out a *lot*.) Given the current 10 year warranty Zodiac (PVC) is offering, it may be worth it to you.
One other bit of info: Buying used will usually save you a bunch of money. You miss out of the steep part of the depreciation curve, and get a boat which has at least some of the bugs worked out. Can be a bit tricky if you're new to boating, but if you know an experienced boater, perhaps you could enlist some help in judging the value of the used boat.
Luck, (and sorry for rambling);