This has been said before by another commenter, but I'll say it again because I think it really is true: Most likely you will never regret taking the year off, but in a few years you probably WILL regret never taking that year off.

> I am worried that I will seem less attractive to future employers when I return

That's not my experience at all. Me and many people I now have huge gaps in their work history, either from travel or startups, and it hasn't hurt anyone.

Also, it's not a black and white decision. Start taking time off and go travel. If you decide it's not for you after a few months just go back early.