We stayed at the Hebridean Guest House in Stornoway as per my review on TMA. Did what it said on the tin, & I'd happily stay there again.
We also visited http://www.eileanoirceos.co.uk/ for the jewllery which was amazing, but the view from the window of her self catering cottage has to be seen to be appreciated - think you'd find something to paint ;-)
She was a nice lady as well.
Course, you could always try a blackhouse: http://www.gearrannan.com/
Another stunning setting (Aren't they all on this island?)
HTH.