We haven't decided exactly which one but we're shooting for one of these:
https://www.vikingrivercruises.com/cruise-destinations/europe/rivers/danube/index.html?utm_id=sem:Brand-Danube-Search-USA-BMM-Phrase&gclid=Cj0KCQjw8MvWBRC8ARIsAOFSVBWOjRu2_O_Zlg-8BJqJ3_Qf6d0sVGIJkdPoBaPT8OGXjxBxrZBYGt4aApZcEALw_wcB&gclsrc=aw.ds&dclid=CJLR7aLRvdoCFQnNZAodjU8ATQ