I can absolutely recommend Glentrail House. There were 11 of us in the house last week and yu could squeeze in a couple more if you're friendly.
Lovely kitchen with big table, living room with log fire, Sky TV, biking DVDs and a stack of Singletrack mags. The rooms are big and very nice, beds are comfy too. Plenty of storage space for bikes, table football, route maps on the walls….I could go on. Also it's right opposite the Hotel if you fancy a pint (Timothy Taylor Landlord no less).
We also had 7 people in the bikelodge which is on the main street. It's a bit smaller and cosier but still nice. Nic the owner works at The Hub which is handy if you're hiring bikes.
Also in Inners is Loch-Ma-Ben which is up the hill opposite the Co-Op. Lovely big house with a garden and has a nice view of Caddon Bank from the living room.
I would certainly go for Glentrail first, followed by Loch-Ma-Ben then Bikelodge.