I've had two GPS units, both made by Garmin. The first was the Vista, which was small and had the capacity to display your position on a map (b&w) but it tended to lose satellite lock in heavy timber or deep canyons. It also went thru batteries pretty quick.
After a LOT of research, I went with the 60CSx. It is slightly larger overall with a larger (color) display, and an external antenna. Most importantly, it has the SIRF III chipset, which is vastly superior. It locks on quickly and stays locked on, despite tree cover or canyon walls. It is waterproof and accepts external memory cards (micro SD) for detailed mapsets. Both street maps and topos are available. Garmin's topos aren't as detailed as a paper USGS, but that level of detail isn't always needed on the small screen of a handheld unit. When such detail is needed, there are other maps available.
I use this regularly in the woods, nearly daily on my bike, have used it with Nav charts when I ahd my boat, and frequently in my truck. It will route and guide you to a destination, but not with voice commands. MSRP is $400 but you can find it for less than $300. Not cheap, but a solid performer.
When I bought it, this was Garmin's flagship handheld. They now offer the Oregon and Colorado units, which have larger screens and some additional features.
-- FLIX
