I have a Garmin Legend C. It's an older unit that I bought for geocaching, hunting and navigating public hunting lands. It's not necessarily the unit I would buy considering my current interests, but it is an effective tool even if it doesn't have some of the more modern bells/whistles. Even the most basic GPS units will be tremendous aids in navigation and marking waypoints on your map. I have learned though, that the GPS is only PART of the equation when navigating and interpreting where you think you are vs. where you are on the MAP. There are a TON of orienteering and map navigation books and videos available, and a lot is free on youtube. I only mention all that because if you wander further than your normal comfort zone because you have a GPS unit, you sure wouldn't want something silly like bad batteries, no signal, etc. to put you in a Bear Grylls situation!
If you're out hunting the boonies, you'll probably find that google earth images aren't as helpful as you thought they would be! Get the USGS topo maps for the quad you're interested in, any aerial maps you can dig up (you'd be surprised what's available on ebay), and even old historic maps can be a handy tool. You may already know all this! I just wanted to pass on what little I have learned in the last few years!
Just for reference, I HAVE had my GPS 'fail' me before when it was the only navigation tool I had (always use FRESH batteries and not a mix of old and new). Luckily it wasn't dark quite yet, I wasn't extremely far from the truck (turned out to be about 1/2mi), and I stayed calm long enough to let logic dictate my next move. It's very humbling to suddenly realize that you've become disoriented! Downright scary to be honest.
Anyway, back to nuts/bolts. You can manually enter coords into all the GPS units that are meant for hiking, etc. and even some units that are designed for automobiles (don't recommend those for hiking naturally). I know the Garmin units are super easy, and I'm guessing all the other manufacturer's will be as well since they all compare very closely in many ways. Along with the ability to mark and store waypoints, you'll be able to enter names for your points of interest into the GPS unit. Most current units have an interface cable and software that will let you download from the GPS to PC, or vice versa. You can load topo maps onto most units now, and many come with expansion slots for more memory. Most will come loaded with base maps of the US which will have city data, but not anything real helpful in the boonies. All the manufacturers sell maps to accompany their units though, and some like DeLorme (mentioned above) can be used with many different units.
I personally like the Garmin units and am very familiar with the etrex series, having owned several, but they have new units, and there are a few other manufacturers out there that are just as good. Again, I'd look at youtube to see what type of instructional videos you could find. Not much info but I hope that helps!
