If you don’t have a burning desire for a place, look for something logical in the flight planning. Something that doesn’t require a lot of train time or flight time or added cost. I googled an open jaw Cincinnati to ________________ and then Prague back to Cincinnati and input a few destinations that were within a 4 hour train or 90 minute discount flight from Prague (either way, it’s a little less than 5 hours door to door). Interesting they all came up with the same price and not much difference in travel time.
An example would be (using British Air)
15 March, Cincinnati to Vienna or Berlin or Budapest or probably several other options (changing at LHR)
Three or four days later, take the train to Prague (<5 hours hotel to hotel from Vienna or Berlin) or a discount airline from Budapest (<5 hours hotel to hotel). So one extra ride to reach Prague. Not two extra train trips or two flights.
31 March, Prague to Cincinnati (changing at LHR).
Price $740.00 (lowest fare class for the international tickets) for all three options + maybe $50 for train tickets or discount airline ticket (lowest air fare maybe $100 with all the frills).
Sorry, dont know how I missed the mid-October travel date in the post. So i checked March.
Wouldnt begin to try and tell you where to go, have no idea of your interests. But will say try what I sugges then plug in some cities and see if anything looks promising.