Dan,
Welcome to the forum! I've got a couple different units. I've got a Magellan Sport Track that works very well, I bought it to replace my Map 330 that died when my computer locked up while trying to do a firmware upgrade. I wouldn't recommend anything but a mapping unit that you can download detailed maps into. My Magellan has 16mb memory (no card, built in memory) available to download detailed maps, this is enough for me to load the entire state of Iowa which is where I use it mostly. If I need anything different it only takes a few minutes to plug it into the PC and change it. If I were doing a lot of traveling out of state I'd look at one that accepts memory cards. I use my unit for work occasionally, it's kind of handy to setup a route to a jobsite on the PC, load it into the GPS and use it to help find the turns.
The map coverage of the base map vs. the downloaded details maps is night and day. The base map doesn't show near the detail of the back waters of the Mississippi river as the downloaded maps.
Another nice feature is the backtrack, you can use it to help you find your way back or you can print it out on the computer for a paper copy. This has worked well for me when I've taken it along to look at some hard to find jobsites, if another crane operator gets sent in my place I can give him a map to find it.
As far as battery life goes my Sport Track is a lot better than the old Map 330. I get about 8-10 hrs. on the Sport Track vs. the 5-6 hrs. I used to get with the 330, they both use 2 AA's. I think some of the Garmins are advertised to run 20-30 hrs. on 2 AA's.
I've also got an Eagle Fish Elite 480(I think the model is right) fish finder/GPS unit in my boat. I needed a new depth finder last year so I bought one that would do both to eliminate one extra thing on the dash. The Eagle has a port for a SD memory card rather than having to hook it up to a computer. I haven't invested in the Eagle software so I don't have a comparison of the downloaded maps against the basemap.
Hope this helps and like Wispete suggests, carry a compass and a map even with a GPS. Batteries go dead and GPS units can fail. I talked to a guy who did search and rescue work with his Golden Retriever out in Wyoming, he said they have seen an increase in people who have gotten lost out in the boonies with just a GPS, no maps or compass.
Jim S