I've also used Garmin units for years...started with the original etrex model. Soon after I bought a Legend model, Garmin released new software that allowed the capability to load about three times the number of waypoints, routes, etc...it was an easy download and upgrade to the GPS unit!
Garmin has upgraded software for most of their units from time-to-time, so you are always able to have the most reliable unit - a great feature, IMHO!
I like to use the EasyGPS software (standard version free) to work with waypoints, routes, etc..it's far easier to load waypoints into EasyGPS on your PC, then download to your GPS unit...you can also upload waypoints from your GPS unit to EasyGPS for security, and save them in any number of files you may wish, to keep track of them...Also, with your waypoints in EasyGPS, you can 'right click' to view a sat picture or road map of that particular place - really neat for checking out places in advance of a visit... a great program!
I'm also currently in the process of loading/saving waypoints for ALL State Parks that have RV facilities...a large task, indeed. The files are arranged by each state, in the 'gpx' file format used by EasyGPS. I'm going to put these files on an 'SD' card chip, and will have some available if anyone expresses interest - will mention it again when I'm finished in a couple of weeks...It's kind of neat, I've loaded a bunch into my 650 Nuvi GPS unit, and I can then select any State Park's waypoint, get the Nav info, of course, and you can look at a local 'map' of that waypoint...and on my PC, I can look at a sat picture of the State Park - and for many you can see the actual RV Park sites - neat!
I've found that several State's are now upgrading their State Park info sites with GPS coordinates, as they've recognized the increased use of GPS units by the public...some are using the D-M.M format, and others are using the D.D format for the coordinate values...this isn't really any problem, as you can convert back and forth, or enter in either format, as needed in EasyGPS...I've found the D.D format is easier to enter and work with, but you can still convert to DMS format for chart work if needed...
GPS is neat stuff to play around with...try it, you'll like it!