I think you're confusing the purposes. I know that Monopods stabilize. But frankly, the vast majority of people I've seen using a monopod are doing so b/c they're shooting with 300mm f2.x zooms for hundreds of exposures at a sporting event. It's more about resting their aching arms. All of the stuff that I typically use a tripod for (such as long exposures...blurring water, fireworks, poi, etc.) I'd never consider using a monopod for--not steady enough.
If you're going to be hiking long distances (and consider using the Monopod as a walking stick) and/or shooting with long/big glass, than a monopod may do it for you. But if you're going to be shooting inside dark, unlit churches with ambient light where your exposure might be 2 seconds than a monopod is a waste of space in your luggage.
Also, it's cruel and ruthless of me to say this but I suggest you pack lighter. My philosophy as a long-time travel has been: if I can't carry it on my back for a couple of miles then it's not going on the trip. I don't do roll-on luggage. I almost never check bags (and never with photo equipment...not since I lost two bags of camera equipment in 1985). I fly all the time with a tripod. If you have so much stuff that you can't fit a tripod in to your carryon luggage, than you're going to have a heckuva time accessing stuff when you're on the go in Europe. You'll see something you want to shoot...but your gear will be back in the hotel or packed in your bag in the hold in the bus. Consider the shooting situations you'll be in (shooting as you go...or shoot, get on a bus/ship/plane, go to another destination, unpack, and then shoot). Or are you going to arrive at a location and then put down roots for 10 days? The shooting situations will tell you what you need to be able to carry and what you can pack and then access.
My advice would be to go with a tripod. And if you've got one that is too big to travel and too heavy to carry around Barcelona or Prague as you walk the streets for a full day, then go the route others have suggested and buy something that is portable.