In reply to Mike Peacock:
Meall Ghaordaidh from Glen Lyon is a good walk, if rather short. It can be extended over Beinn nan Oighreag as well. Route here:
http://www.walkhighlands.co.uk/Forum/viewtopic.php?f=9&t=61976
Don't bother going up it from Glen Lochay as it isn't very exciting from there (even though that's what everyone does, giving it a bad reputation).
A good long day out would be a circuit of the Beinn Lawers Munros from Glen Lyon. I know you said you didn't want Ben Lawers again, but this does give a different, much wilder perspective on it.
Creag Mac Ranaich above Lochearnhead is quite a nice hill, and I'd strongly recommend a trip down Loch Voil to Inverlochlarig (obviously getting a little further away from Loch Tay now). You could get onto Stob Binnein or Cruach Ardrain from there, or Stob a' Choin to the south (one of my favourites). Really scenic area.
Make sure you set your companions expectations correctly on some of the less-trodden routes though - particularly around Inverlochlarig. The going can be quite hard away from paths, and if they are used to Wales or the Lakes, it could come as a bit of a shock!
Post edited at 18:04