My appartment is less than one minute to line 1 and 8 (Reuilly-diderot). It's a nice place to stay if you are planning to visit Paris for few days.
If you are four people coming, just be careful with the use of water to be sure that everybody can take a shower. :)
The room has a wall communicating with a stairwell so sometimes you can hear people going up or down but it's quiet most of the time, and definitely during nightime.
let me know if you want to stay longer, I can open the calendar !