10 years ago my now wife and I stayed nearby at Hotel Albe, and fell in love with Saint Germain, specifically the Saint-André des Arts corner near where Lory and John's place is. Yes, it can be loud at night (and into the wee hours of the morning) and there are throngs of tourists everywhere, but there is a lot to offer in the area, and the Saint Michel station connects to numerous Metro lines and the RER for venturing out. We laughed about how poorly the Hotel Albe's windows kept the noise out and how tiny the room was. We were younger, had just met, and were falling in love, and so didn't care.
We could not have been happier with decision to stay at Lory and John's place for our "anniversary" trip. Though not much more costly, their place is huge and well noise-insulated while providing all the amenities and appointments you'd expect from a hotel, plus the benefits of staying in a proper home. There are several flights of ancient, steep, narrow, uneven, winding stairs to negotiate, but nothing able-bodied people should be too concerned about. John was responsive and was waiting to greet us, and offered local guidance, but we already know Paris and so didn't need the input. Highly recommend!