Achnabreck (*****) is the must, must see. If you want low light, go late not early as the trees get in the way in the morning. Open views to the west. And don't forget the other panel further up the hill. Surprising how many miss it!

On the other main rock art sites , you can drive to Kilmichael Glassary (***) but its heading away from the rest of the sites so you might want to leave it. Baluachraig (***) is by the road and Cairnbaan (****) is a short but steep climb from the road. Ormaig (****) is a long walk so you'd have to give up a lot of the rest to go there. Worth seeing though because of its rare design. (A lot of the other panels are usually under turf). Poltalloch (***) nice site but a medium walk. Ballygowan (**) probably not worth the walk.

Basically, if you just do Achnabreck, Cairnbaan and Baluachraig for rock art you should have enough time to do all the other signposted main non rock art sites and the museum (provided you have a full 9-7 type day). They're all close together.

Have you got the book?