I'd suggest a garmin handheld too, I've messed with them some and have a pretty fair knowledge about them, I have a vista HCX and am picking up a summit HC for my son in just a few days
garmins handheld units are good units... highly functional, easy to use and the etrex line is somewhatbetter price-wisethan other GPS units in thier range
their product line is kind of confusing but I'd stick with the "H"(high senitivity" model etrex'sor the high sensitivity "GPSmap" series(60 and/or 76 models) if you live in an area thats remotely hilly and/or forested, the "H" modelskeep and hold a lock in any terrian whereas the older models can easily loose their signal lock
the higher end models are the best option, the legend HCX and the vista HCX are the better ones, both have pretty much anything you'd need in a GPS for both on and off road use, the "X" stands for external memory which means use micro sd cards which gives them way more memory and/or memory options than the non X models that only have limited internal memory, and with the city navigator maps they're also surprisingly comparable performance-wise to a standard road use GPS, they auto route, have turn-turn directioning, address finding, a whole world of on-road features... the only real difference between the two is the vista HCX has the electronic compass where the legend doesnt
the basic "H" is the cheapest, its a non-mapping unit thats easy to use and has just enoungh features to get you around, the venture HC and summit HC are basically the same unit except the summit has the electronic compass and altimeter and the venture doesnt(just like the legend and vista HCX's), neither auto route or have external memory
a few other things to consider is usage, battery life, customer service, unit size/layout, system bugs, ect., I bought my vista HCX because I wanted the whole works, the venture HC I'm picking up will be for off road use only so it only has to store a few topo maps,its perfect for what its going to be used for, its perfomance is still the same as the higher end HCX and its alot cheaper
you also have to keep in mind that although they work decent with the usless base maps they come with they really function the best with the higher end maps, either topo for off road use or city navigator for street(if the unit is auto route capable), both if the unit is capable of storing/using them, the maps have to be bought seperate and arent cheap, a good set of maps can sometimes run almost as much as the GPS itself... topo maps can be downloaded to any unit but the city navigator maps are sold with an unlock code and can only be used once with only one unit... thereare some pretty decentfree maps around though that people have put out, and you can make custom maps if you have the ability
I'd check out garmins site,
http://www.garmin.com/garmin/cms/site/us
I'd also check out the geocaching forum
http://www.garmin.com/garmin/cms/site/us, theres a ton of info on GPS units there