For desk top scouting I prefer Google Earth Pro as my main viewer. My favorite feature is the ability to overlay any map, from any source, onto the GE maps. This unique feature allows me to compare information between ANY two maps on the internet by sliding the translucency slider back and forth, often revealing things you would not have noticed otherwise. Some of my most useful overlays for scouting are....
-Caltopo... "scanned topo" base layer with "shaded relief".."normal"...stacked on, set at 50% transparency. This gives a nice 3D effect. Then save that map in GE and you will be able to see the 3D topo over any aerial you have.
-Lidar DEM hill shade view, overlaid over any aerial you have in GE. This shows subtle points, humps, secondary logging roads, man made alterations to the land, in extreme detail (topo's don't do this), again...layered over any other map you want. This layer is eye opening!
-GIS county aerial taken in late October in my north woods hunting area (clearly showing oaks holding leaves vs all other hardwood trees being bare). I layered this into GE, drew a white line around all oak clumps of 1 acre to 6-7 acres in size. Now I can see where isolated oaks are located in relation to typical bedding terrain. It feels like cheating!
GE Pro also allows me to save hi resolution aerials as KMZ files. What that means is I can make custom aerials and put them on my GPS. What I do is layer things like property borders, isolated oaks, access paths, stand site locations all onto one aerial, and use that as my in field navigation map while hunting/scouting. Works great, but is a bit of home work to accomplish. But Beasts aren't afraid of work!