In reply to Dave the Rave:
Rois Bheinn is part of a wonderful round of three Corbetts, but that'd take more than half a day for most. But if you don't mind just nipping up and back down it and coming back another time to do the round, you could easily do it from the west and it's a lovely hill.
If you're Corbett bagging and just want to take the chance to knock one off the list, your best bet is probably Sgurr an Utha, NW of Glenfinnan. I don't remember it being well pathed, though!
If it doesn't have to be a Corbett, there are a couple of rugged, lovely hills - Carn a'Ghobhair and Sgurr Bhuidhe - that you can do by way of a good path from the south end of Mallaig. Both are under 2000', but it's a great bit of countryside.