I completely concur with previous comments about the quality of this area. The Kilmartin House experience is certainly worth the time and £££, as is their publication.
Recommend you start by visiting Dunadd to put the Glen into some context.

While in the area you should visit Crinan just to soak up the coastal fringe atmosphere........depending on where you're staying it's walkable. I was fortunate enough to blag a sailing trip from there all the way to Mull and back.