A nice no frills gps to consider is the Garmin Etrex.
If you want all the extra doo-dads, be prepared to pony up some cash, but do you really need to know what the barometric pressure in Zaire is?
I've used my Etrex everywhere from on top of my tank in Ft Lewis, WA, to Ft Polk, LA and in my Heep all over the country, and I really have no complaints. It's been dropped off the top of the tank, and subjected to the PNW rainy season (like there is a dry season) and it keeps on ticking. I prefer to use the MGRS(military grid reference system)
I actually did a side by side with the military's PLGR (high speed gps with the security code) and there was less than a 5 meter difference between the 2
HTH
John