Hey Molly,
I've only stayed in hostels the two times I've been to paris, and both experiences left something to be desired, so i endorse your decision to avoid them. A couple friends of mine stayed at the Hotel Britannique and LOVED it. Here's their site:
Link
They said it was pretty much right smack dab in the middle of the city but that it was also surprisingly quiet. Granted they only stayed 2 or 3 nights. 10 days is a long time to stay in one hotel, but hopefully this is a start!