Apartment is the way to go
 

Holiday flat rentals abound in Paris, and a new agency seems to pop up every day. Suggest you take a look at www.kudeta-home.com - we were quite pleased.
Would suggest that whatever agency you use, for a visit in July an apartment with AC is well advised. Last year it was beastly hot in July!

I've stayed in this rental for a week in the Latin Quarter. Very convenient to transit, and there is plenty of nightlife (although more student than GLBT).

http://www.rentalfrance.com/index.php?location=huchette

I really enjoyed the location, and despite being on a rather busy street, it was quiet. The windows opened to an interior courtyard.

The only downside was that the bed "room" is actually a loft (you can see a bit of it in photo #7) Not enough room to stand up and having to navigate ladder-stairs for middle of the night trips to the bathroom was a bit awkward.

The owner was very helpful and friendly, and I believe has multiple properties. I wouldn't hesitate to rent from him again.

Didn't trust me? ;) I have a photo of the Jewelers that I emailed some friends in Canada and the US, they loved that place (well the bar anyway). I actually had heard really horrible things about the hotel, but that was because of misguided expectations I believe. When there is a shared bath and toilets in Paris, especially 30 years ago, expect one or more of the toilets to be of the squat and hover variety....

There is also an excellent gay home exchange program called Home Around the World (http://www.homearoundtheworld.com) which I have used a few times and have found to be very good.

If you can agree a swap there are some nice places in Paris (inc the Marais as you might expect) although they tend to be small by US standards (as again you might expect!)

Have a fun trip

Fritz