If you're just looking for a meeting place, the Green Welly Stop is pretty central and quite popular with bikers. It even got a "loo of the year, 2009" five star award! http://www.thegreenwellystop.co.uk/
If you're doing a stay-over event the Argyll Hotel in Inverary is biker-friendly and has some fantastic views, plus a suberp range of malts: http://www.booking.com/hotel/gb/argyllh ... 3d406d0a53
If you end up riding up the west coast, make sure you stop off at Kilmartin Glen. Stone circles, cairns, ancient rock art, a truely remarkable churchyard (check out the Templar gravestones) etc: http://www.undiscoveredscotland.co.uk/k ... index.htmlhttp://www.undiscoveredscotland.co.uk/k ... index.html
On the east cost, I can recommend the Scottish mining museum (maybe I'm biased - I did mining etc as a degree course!) but if you can organise a tour of the "large object store", there will be things to interst anyone of a mechanical bent: http://www.scottishminingmuseum.com/museum/index.asp
I can also orgainise a special tour of the Edinburgh City Observatory for you* - during the day, you'll only get to see the site - for an evening tour, you can get to see the sky through the scopes as well (don't blame me - you can't use telescopes in the daytime: also, don't blame me if its couldy - I don't control the weather!)http://en.wikipedia.org/wiki/City_Obser ... _Edinburgh
(* one of the few fringe benefits of being a previous President of the Astronomical Society.)
If you get the dates right, a trip to the 1/4 mile strip at Crail is well worth it. I've done a fair few timed 1/4 mile drag runs in my life - most strips have a huge "run off" area, but Crail is different: get it wrong and you're straight into the ocean. Their website is so crap that I won't even post it.
Let me know what date(s) you plan things for - hopefully I'll make the run up.