Elbe Hills ORV park just outside Ashford WA (go up Stoner Rd to gravel and keep going) has some good winter wheeling trails.
The West entrance to Little Naches through FS70 off hwy 410 (Greenwater)is alot of fun. It does close to snowpark during the winter but I highly reccomend running it in the spring when the mud is deep and the trail is sloppy.

Still some good spots along the I-90 corridor but public forum isn't the place to post them.