Hermione Granger (Harry Potter)
She's smart and savvy- perfect qualities to have when exploring foreign streets. Also, as proven by the 7th book, she'd always have everything you could possibly need to travel in her purse.
Not to mention, Hermione is awesome. Period.
I'd like to say I chose him because he knows London well and could show me around, but that's only partially true. My real reasons are, truthfully, much more shallow.
Radar (Paper Towns)
He's Q's best friend in the book, who constantly obsesses over Omnictionary. (Basically, the fictional version of Wikipedia.) With all of that encyclopedia knowledge, he'd definitely come in handy. Even if he does need to pee every half an hour, I'd still travel with him.
Victoria (Audrey, Wait!)
She's assertive and totally (pardon my French) kick-ass, plus she knows how to have fun while still being sensible. Victoria also has a great sense of music and she's a fantastic friend to Audrey. All of those traits seem like good travel qualities to me!
Which character would you like to travel with?