Google Earth Pro is free and is super easy to make KMLs (as well as Shapefiles and other GIS files) in.
Since it caches image tiles it can be used (in a limited fashion) offline too.
When online you can look through historical imagery of your area of interest, which can be really useful for a variety of purposes.
CalTopo is ok, but I think there are a lot of better, or equally good, options out there.