They are great for marking spots that you find that you want to return too as well. I have had the Etrex Vista, and now have the Rhino 120. I got the 120 for the handheld radio capability. Wasn't worth the extra $$. Get ine with a compas and mapping capability, even if you dont think you need it now. The map overlay is awesome when trying to find that elusive "shortcut".
As all have said, make sure you are competent with your compass. Batteries die, signals can become weak, etc....