FYI I merged the two identical topics into one.
Wow, how on earth did you manage to score a last-minute two month trip to Europe??
Basically in two days and no chance to try anything on the odds are that you're going to get something that doesn't fit very well. Are you tall? Short? Wide? Thin? Male? Female? Those are key criteria in pack fitting. Personally I like packs geared towards mountaineering and hiking rather than travel. I have a Marmot pack and it's fantastic. But other people have more "travel" oriented backpacks such as Eagle Creek and they love them.
It's up to you, dude. You're going to have to pull the trigger blind, unfortunately. Good luck and have fun!