My wife and I put in our 10' kayaks at a small boat launching site on the north side of upper Manatee River Road about 1/4 mile west of the Rye bridge. We paddled upstream probably about 1 mile(near the Rye Preserve) before the river became to shallow to go any further. We then simply turned around and went back to the starting point and we were probably on the water for only an hour. The Manatee is a tidal river and there are times when you can go all the way to the dam on Lake Manatee. Going downstream, you can go all the way to the Gulf of Mexico. There's a picturesque section of about 4 miles and there's a place were you can rent canoes and kayaks (Ray's Canoes). It's a great place for a beginner to take a nice ride.
All kinds of hotels and motels in Bradenton.
From Bradenton take State Rd 64 east to Upper Manatee River Rd. Turn left and follow it until you come to Ray's Canoe rental or the launching site. (10-15 miles from Bradenton)