Riverboat cruise through Amawaterways up the Rhine from Amsterdam Netherlands to Basel Switzerland. Absolutely spectacular scenery and history. When all this dies down, I'd consider it again.
River cruises are great. Lots of fun stuff and tours at stops. 200 people, not 2000. Entertainment every night.
In addition to the Rhine, try the Danube. Their old palaces make the US Capitol look like tinker toys.
History themed river cruises: Down the Columbia and Snake Rivers with Lewis and Clark stuff.. Down the Mississippi from Memphis to New Orleans with Civil War stuff.
As for ocean cruises, Alaska on the inside passage is great in July. I liked Tahiti in a 4-masted ship. Never went on a Caribbean cruise and don't care if I see the Panama Canal.
If you never tried a cruise, you don't know what you're missing. ALWAYS get an upper deck room with a balcony. If you can't afford that, don't go.
