Hey Julie, mutual! So great that you have so much time in Scotland this year. I've been there three times, and love it very much. Don't know when we will get back there, so many places to go. But it's definitely a favourite of mine.
I too would love Venice to Istanbul, or something like that, in the Aegean/Adriatic of some sort. But in the spring! Regent doesn't seem to do much eastern med in the spring, so we may be stuck with O, or just do a land trip (we have friends who spend a couple of months in Crete every year, and they have been inviting us to visit them.)
I don't mind a mix of land and cruise, as long as I can park my cruisewear somewhere so I don't have to lug it around. We tend to try to plan it so we're not relocating every night, and dress very casually when we're travelling that way. Love the freedom of a little car when appropriate to let you follow your nose, or just spend an extended period in an interesting city, like Istanbul or Amsterdam (2 more favourite places!)