I use SkyDemon, planning usually at home on the PC and then transferring the route to my HTC HD2 phone for use in the cockpit. Although the functionality to plan is available on the phone it's obviously easier to do that on a big screen.
I can get the notams/weather etc either on the PC at home, or if it's a route I planned some time ago use the phones internet connection to download them at the airfield. They still get displayed on the map on the phone in the same way they do on the PC.
If it's just a local bimble with no particular route planned then I'll check notams with SkyDemon when I am at the airfield, but then use Memory Map and the CAA charts just so I can confirm location once airborne.