I vote for Aberdeen!
Well, seriously, railing over europe is no big problem.
Do like London-Paris-Venice-Munchen or something, all great places.
Well, London is getting kind of expensive, and Venice is full of tourists except mid-winter, Munchen is nice, Paris is great, Bruxelles looks good, - emmm,,,,full of good places.
Or do the south, Rome to Athens, consider a ferry from Brindisi to Greece perhaps.
Then there are the Mediterranian cruises also, like an 8 days circle of the inner med, Italy-Greece-Istanbul-Malta or something in that direction.