overnight in paris, from London

We are going to London and want to do an overnight to Paris. We found one tour company that gives a guided tour the first day, then gives you the second day on your own. We've also thought about doing it on our own. We've never been to Paris,and do not speak French, so we're not sure what to do. If we do it on our own, where would we stay to be close to main attractions? Thanks for your input. Karen