We are cruising on the Avalon View from the Black Sea (Romania) to Vilshofen, Germany, 17 nights embarking October 14th. The cruise goes through Romania, Bulgaria, Serbia, Croatia, Hungary, Slovakia, Austria and Germany. We're excited to do this cruise as it seems likely to be more exotic than the Amsterdam-Budapest route. However, the multitude of currencies that are not useable outside the host countries makes planning complicated. Anyone done this route? If so, how did you manage transactions? Even using credit cards it seems some cash might be good to have on hand. Thanks for any advice.