I have a single 20amp regular circuit but it has two separate
GFI outlets that I carefully distributed the load accross in case one trips. When you get close to the limit on the GFCI something like a light firing up or a motor start could trip it. The one in my garage occasionally trips when I start the circular saw up. Typical GFCI outlets used in bathrooms are only 15amp so it doesnt matter then if the breaker is 20amp or not. I haven't looked but you can probably buy 20amp outlet GFCI also. Personally I like the outlet style becasue if it does trip it is easier to reset than heading for the breaker box.
