You do not need to reach a summit to have a good day out, there are many "wilderness" walks in Scotland, that give a excellent day out.  Indeed many parts of Northern Scotland are the only real wilderness areas we have left in Britain.

Cape Wrath coastal walk   ~  Oldsmore to Cape Wrath (16 miles) then Cape Wrath to Kearvaig Bay (4 miles)
the route passes differing landscapes as Sandwood Bay, and Am Buachaille sea stack.  When you have finished the walk it is a ferry journey and a hitch hike back to your car.  Due to this and the remoteness of the area it involves a night in a bivvy or Bothy (unless you are supper fit).

The day in May1993 when I walked the route it rained and we did not start to mid afternoon, hence it was very late, and very wet by the time we reached the Bothy.