BpackerDon mentioned that National Geographic has something like what you're looking for and really, it's best to get their "TOPO!" software and purchase the topo maps for your State and those you visit most. Then you can place waypoints on the maps, and even draw routes on them, and upload them to you GPS. You can also download them into your computer from your GPS and view them on your maps. You can also print the maps you need and take them with you.

There are other software packages that work pretty well too. I use "TopoDraw" on my Mac. It looks like it's been discontinued though. It allows you to download free quad maps and use them to set waypoints and draw tracks, then upload the data to your GPS.

And, if I'm not mistaken, Garmin has good topo map software that runs on PCs or Macs. If you have a Garmin GPS that's a good choice.

The bottom line is that using a GPS requires a learning curve to be met and it's well worth the effort if you're a lover of maps. You don't need one to go backpacking, but they're a fun and handy tool to have.

That said, I use mine for all the reasons you mention except geocaching, which I've never really got into. I also use it to mark waypoints. I often share waypoints, tracks, and routes with others, but I don't know of any great sites where these are shared. National Geographic tried to do this on a web site, but it never really took off and I don't think they still provide that feature on their current "Topo.com" site.