The best I've seen is Topo (by Nat'l Geographic). It has much more detail (7 CDs for WA state) than my Garmin maps (2 CDs for the entire lower 48). It uses the USGS 7.5 minute maps which show trails, FS roads and usually a 40' contour interval. Topo imports & saves GPS tracks or can create / export waypoints back to the GPS unit.
It also allows you to print your own maps (with or without tracks) which is handy for new areas or boondocking expeditions.
Reg price is $100, I've seen on sale for $75. Might do better on-line or Ebay.
There are a number of sites that have downloadable snowmobile area Topo maps created for WA (numbskull.com, wssa.us, etc).