Killin is lovely - a real picturesque village with plenty of B&Bs, pubs etc.
If you're feeling adventurous, the walk up Beinn Ghlas (near Lochan ma Lairige) follows a good path. It's more straightforward than many hills of its size, although it's by no means a walk in the park. It would require a 15min drive to the start, though, from Killin.
The Rob Roy Way passes through Killin and gives great views of Loch Tay and the Lawers range of hills to the north, including Beinn Ghlas. The section that heads east from Killin initially follows a good, undulating, path over moorland, then joins a single track road to the south of Loch Tay.