It would be good to go on one just to cause havoc. Like wandering off from the tours and turning up back at the boat a day later worse for wear. Maybe with a few local 'mates' in tow. My late mother went on a med and near middle-east cruise though and she thought it was excellent.Take a cruise ... the idea of being on a ship with 2000+ (and usually a LOT more) people where the primary things to do are eat and be herded around various shore-based tourist traps ... no thank you!
Things I have no desire to do:
Go to Santiago de Compostela. Who can go to these places now that they're a postmodern 'must'?
On the whole though I'd probably do a lot of things I can't do because of either finances or opportunity or whatever.