Oban is a very nice trip from Glasgow. As is Stirling.
The first is right on the sea, and you can get some excellent seafood there. You can walk up the hill to the big thing (I am forgetting the name at the moment). There are some nice shops and the air smells like a typical fishing villiage...very nice.
The second is a great day trip. You can easily see the castle, then walk to the Wallace Monument (over the historic Stirling bridge). The cemetary at the base of the castle is great to check out, if you are into that kind thing.
There are some really great places to stay and eat in both places.