What's a good river trip for March?

You could look into Lake Okeechoebee (sp.?) in Florida. The weather should be good for it; but you want to find out about the water levels. I don’t know canoe rental rules.

My brother used to spend a lot of time here He loved it.

If renting a canoe requires someone of a certain age, you’re going to have to provide one. Otherwise, plan something else. Simple as that.

I agree with @janbb that in March Florida is the way to go. The weather is usually ideal in March. Very little rain, springlike temperatures, but there is no guarantee of course. In March you will be better off staying towards the very southern part of the US or you risk very cold weather.

I found this site and this site for places to canoe and kayak in FL. Probably FL tourism could help you too. Each state would have similar information and their are sites for top ten places to canoe in the country, but some of those could still be in the tundra during March.

Depending where you are coming from FL might be very far, so do consider southern states more west also. FYI in some parts of FL the week before Easter and the week after are the most expensive and most crowded with tourists.

Depending on the area of the country, a river might be in flood that time of year due to snowmelt. When I was in the Army National Guard they decided to take us all canoeing. The Snake River in Idaho was in flood in March, but we went anyway. I was nearly killed when my canoe turned over and I was swept downstream.

It’s best to ask someone who knows before you get stuck somewhere.

I had a great time canoeing in Rockford, IL. Basically, we rented canoes, brought/drank beer, and floated down stream. After so many hours, we drifted to the pick up point, and the canoe company drove us back to the parking lot upstream.