Wife and I did a European cruise on Viking a few years ago-Budapest to Passau Germany, then up to Prague. Was, without doubt THE best vacation ever. Vikings riverboats are small (180 passenger), no kids, no casinos, no pressure. Everything was first class. We were satisfied enough that last year we went back on a Viking sea cruise in t he Med around Italy-Greece. There is NO other line I would even consider. Haven’t done the Mississippi cruise simply because we have already been everywhere it goes (drove the river road). With that said, seriously consider the European cruise-last I looked you could actually do one for less $$ than the Mississippi cruise.