Swakane was crowded last year, but there was more snow then. Probably more hunters as well. I saw 15 trucks in one day. I don't mean to turn you off of the unit, but be prepared to get away from the roads.
I don't have a deer tag now (already filled it!), but I would look into Derby Canyon, Rattlesnake Spring, or Chumstick Mountain. Sorry I cannot help with Sinlahekin.
Brett