My wife and I stayed in this place earlier this year...

http://guide.visitscotland.com/vs/guide/5,en,SCH1/objectId,ACC5973Svs,curr,GBP,season,at1,selectedEntry,home/home.html#contactDetails

...and I couldn't recomend it highly enough. It's really nice and cosy and has amazing views of the coastline. Best of all it has a open peat fire for which peat is supplied, and has an Aga-type stove in the Kitchen. It's not particularly close to Callanish, in fact it's closer to Clash An Trushal. There are a few other sites well within walking distance. Callanish is about a 20-30 mins drive away.