It's also great a few days later when you're checking out to catch an early train. You don't have to worry about busses or cabs or anything. Only bring one bag. I really swear - really. Taking five years of French doesn't help you understand French.
Hostels are no good for light sleepers and germ-freaks, but the price really is right.
Just be mentally prepared for huge rooms with 10 to 20 beds and splurge on a real room once in a while so you can take a hot shower. I didn't pee or wash my face or do anything in there. But, you have to shower somewhere, sometime, so bring along a pair of 99 cent flip flops - the kind you've been buying since girl or boy scout camp. Send a postcard to yourself from each city. You'll have a great collection when you get back - if you ever come back.