Garmin pretty much makes you pay for everything extra. Here's pretty much what I do:
--nonot has compiled topo maps, hydro data, and routes that you can download here:
http://www.hikearizona.com/garmin_maps.php--you'll need also to download a free program called Mapset Toolkit to install them into your Garmin Mapsource software
--when I hike I have the route, hydro, and topo maps of the area loaded onto my Garmin but I usually have the topo map turned off unless I need it because it seems to slow down my Garmin and complicate the screen. If I need it for reference, its always there though. What I do to keep reference points of the area's layout without keeping the topo map up all the time is set waypoints for peaks, geological formations, springs, etc. The route and hydro maps are pretty small and I keep those on screen even though I usually have a preloaded track of my plans for the day (unless its something I've done a bunch of times).
--one important thing to note is that your GPS does not replace your compass. It only points the correct direction while moving which can make things very confusing if you've stopped and are trying to figure out where you are.