In reply to Taurig:
I've not been there for a few years, but the Creggans Inn at Strachur (on Loch Fyne) used to be a favourite of mine. Great bar food and the restaurant was exceptional. The Loch Fyne Oyster Bar isn't too far away, and Fyne Ales (Cairndow) is just along the road too - well worth a visit if you like your beer.
Hill-wise, it's handy for the Arrochar Alps.
If you fancy this idea, make sure to check that the Rest and Be Thankful road is open, as it's been closed a fair bit recently because of land slides.