I'm thinking of doing an open ended trip to Europe. Seems kinda scary not having set plans but I don't want to be constrained by a schedule for a variety of reasons. Anyone done this? Am I thinking crazy?
I have. Is there anything in particular that worries you?
The cost of making arrangements on short notice
If you're talking booking a return flight from Europe to America on short notice, yeah, you'll probably get pinched.
If you're talking about traveling within the Eurozone, I never really noticed a difference. Can't speak to plane tickets, as I never bought one day of or day before, but I regularly did for trains and buses, and it was fine. I have bought plane tickets, say, a week before, and was able to find reasonable prices. Travel by rail, if at all possible.
In terms of lodging, are we talking about hostels, hotels, or AirBNBs? AirBNB would generally be the way to go, and there wouldn't be a premium for booking an available place the day before. But you can't really book an open-ended AirBNB stay, obviously. Can't really speak to hotel pricing, and you don't strike me as a hostel guy.
Also, you can bounce around the Schengen countries (basically, all of Europe) with ease for up to 90 days without needing a visa. Perks of being an American. You will need to arrange a visa with one of the countries if you plan to stay longer than that.