I know you can get topo maps to load into the Garmin devices, but they are not the USGS quads, of course. Garmin only has 1:25,000 scale coverage for the national parks, though. That said, trying to read a topo map on a 2" handheld GPS screen is pretty much an exercise in futility. IMO you're better off carrying the paper quads around if you want to be able to look at a map. The strength of the GPS is that you can track yourself so you can backtrack easily, or, alternatively, create routes on the computer at larger resolution that you can follow in and out.