Me and Wife planning a 8ish day European Vacation

To start it off we’re American and have never been to Europe, the only place we’ve been out of the country are resorts in different countries in the Caribbean. We are planning this trip the end of June and her “no compromise destination” is Paris and Disney in Paris for some unfortunate reason. I’m more interested in the architecture and culture of Italy (Florence, Rome, Tuscany area). What is worth seeing and not, is it worth maybe getting on a cruise over there to be able to check out different places? I don’t want to go on vacation and feel rushed to do everything. For my experienced travelers what were your favorite spots and the ones you wish you had skipped?