Saw your square back vs double ended canoe post on the advice board, so i will attempt to answer both here.
Square back canoes tend to be heavy and wide. Good for stability, poor for carrying and paddling. You can easily mount a small outboard or trolling motor on a double end canoe.
For a first time trip, considering your wife's need for facilities (I am guessing toilet and shower house would make her happy), i would suggest going to one of the state campgrounds that are on water. Fish Creek campground and the connnected Rollins Pond would best suite your first trip. From either one you can canoe a nice easy loop thru calm ponds and streams. Then return to your base camp with facilities and places for the young ones to burn off energy. All the sites at Fish Creek are on the water, you can boat right from your campsite. Rollins has the majority on the water and the rest are just across the road from it. They do fill up fast so make an online reservation as soon as possible.
Near Fish Creek are outfitters than will rent you different models of canoes. That will allow you to try different models and compare them. Mac's Canoe in Lake Clear is within 10 minutes of the entrance to Fish Creek and they are good folks to deal with, both in rentals and purchasing. There is another outfitter south of Tupper lake right by the bridge where the Raquette River comes out of Simon Pond. Mac's proximity to Fish Creek would be the most convenient.
Fish Creek and Rollins Pond are just outside the St.Regis Canoe Area where most of the water is off limits to motors. Good places to begin your canoeing, and build up your skills before you venture out on the big lakes with big waves and big boat wakes.
This year work on experience and finding the right canoe for your usage. Then in 2012 you can tackle and easy wilderness trip thru the St. Regis Area or down the Raquette River from Long Lake to Tupper Lake, or back into the Lowes Lake/Bog River area. There are free first come first served campsites in all three mentioned areas, but their facilites are limited to an outhouse, fire ring and picnic table. For bathing, you go swimming. For drinking water,you filter or chlorinate.
For a canoe my personal reccommendation for your usage would be a 17' composite canoe such as the Wenonah Spirit II as the minimum size. The outfitters can put in several for test paddles and you will quickly find out what you like. Buying a canoe you will balance your wallet against your back. The lighter canoes become, the more expensive they become. Its not carrying the canoe to the water that determines how much weight you can handle, its getting back up the bank and onto the car at the end of each outing. Anything over 75# is heavy with a capital H, between 55 & 75 is manageable, and under 55# becomes more fun and less work, especially under 50.
Polyethylene canoes (coleman ram-x, Old Town Cross-Link3, Mad River Triple Tough, etc) will be heavy even in short 14 & 15 foot canoes. Royalex canoes will be manageable and more expensive. Fiberglass and Kevlar canoes will be light and even more expensive. But the difference between the least expensive and most expensive spread over 20 years or even 10 amounts to a cost equal to dinner out with your family each year.
For family paddling with differents sized paddlers in the bow, look to buy a canoe with a sliding bow seat option. For your back make sure the canoe has a carrying yoke at the center of the canoe. Not a tubular thwart or molded in seat, but a yoke.
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