Potentially Least Expensive - USAPhotoMaps
If you're satisfied with a "no frills" but capable solution you might consider USAPhotoMaps (
http://jdmcox.com/). You can download and run it for evaluation for free. Registration is only $20.
It combines 7.5 minute topo data with 1m resolution digital aerial photography (DOQ). The data is free since the program interacts with the Terraserver website and downloads the data you need. Additional data such as United States Geological Service Points of Interest (bascially anything labeled on a USGS Topo map) and TIGER streets (roads and trails - amazingly complete but not perfect) can also be downloaded for free. The program works well with Garmin GPS units - either in real time to show your current position on the aerial photo or the Topo map, or by downloading tracks or waypoints from the GPS unit into the program.
A complementary product called TerraFetcher can download Topo and aerial photography data outside of USA Photomaps - greatly speeding up the process.
Either way you download the data, it is stored on your hard drive so that you only need to download it once. Thus you can get all the data for a trip while you're connected to the internet and then go offline.
Advantages:
Inexpensive program, free data, reasonable suite of features, program takes little space.
Disadvantages:
Documentation limited to a free-form help file (its all there but hard to find), program works within UTM zones (6 degree chunks of longitude) but not across them (if you scroll across a UTM zone boundary you jump to the next zone but you can't see areas in two zones at once). Downloading data takes some time, but there is no post download processing required.
I have several mapping programs that I use - ArcView (expensive GIS software), Delorme Topo USA, OziExplorer (I've only recently started with it) and USAPhotomaps. For simple route planning and recording I find myself using USAPhotomaps a lot.
Good Luck!
Howard L. Snell