Depends what you want to see and do, Castles , Mountains, stunning coastlines ?????? If you're heading up here from the lakes then you've broken the back of the journey tbh. I lived just south of Kendal for 5 years and Glasgow is approx 2 hrs at 75/80mph so the lower highlands are well within reach as is some great west coast scenery.
Either email me or give me a call and let me know what your hoping to see/do and I'll make some suggestions which you are welcome to inspect in the comfort of your own home for 10 days with no obligation, and no salesman will call ! You may even keep the free gift.
Toodle Pip
PAul
ps. The Avon only works for some people, some people swear by it, others including myself only find it a nice smelling skin softner which does sfa to repel the dreaded midge !
pps. Mike ( Boxertools ) Spelling is Corryvreckan, but you were close
It's actually the Gulf of Corryvreckan, and the Corryvreckan itself is a whirlpool, though it'd be more acurate to say Maelstrom ( tides can run up to 10 knots ! ) created by the underwater topography of the sound and the tidal rips from Jura. Used to sail through it a lot as when I was doing all my sailing we tended to base at Ardfern but would often sail round to Croab Haven for a few jars before catching the early tide. The whole gulf is impressive depending on the tide and wind state and once through to the west you have the Great Tidal Rip which is also pretty impressive. It's not that far from land and you can actually moor off Scarba and walk round to look down upon the whole event. It's certainly not a passage to attempt unprepared, get your tides wrong and you'll be going backwards at best ! get them right and hold on to your hat, it's a hell of a ride. 
. We should try and avoid the snow, so sometime between May and September would be best. Suggestions for a base camp? Stirling? Pitlochrie? or a bit further North?