I am sorry that you won't be joining us.
We've never been to Istanbul, either, so this is very exciting.
I know what you mean about limited vacation time. I am very limited; however, my husband has weeks and weeks.
You will love Venice, if you've never been. If intersted in a walking tour of this lovely city, check out Walks Inside Venice -
www.walksinsidevenice.com. Our tour guide, Roberta, was wonderful. She got us into The Doges Secret Itinerary Tour without any crowds, whatsoever. This is a very popular tour. If you contact them for touring, please be sure to request just Roberta - we had another guide, Christine, who took us around one day and she is no Roberta!