LG: Try the Merrymeeting Marsh/River. There is free parking and a boat ramp on Rt. 11 near the New Durham town line. I'd estimate that it is about 5 miles of uninterrupted paddling from there down to the first dam in Alton just past the fire station. Lot of birds and other wild animals to check out. By all means bring your camera!
"The Merrymeeting State Wildlife Management Area on the Merrymeeting River offers superb quietwater paddling. One could spend hours paddling this waterway, absorbed in the marsh’s biologically rich wonders...." from trails.com
Also there are some public ramps on quieter, smaller lakes where you won't be bothered by big wakes such as Crescent Lake in Wolfeboro, and Manning and Crystal Lakes over in Gilmanton.