Nice find!
We had a good experience at Michaella's flat in the 17e. It was close to the Arc de Triomphe and about 1 block from a shopping mall. The gourmet store and grocery stores were exceedingly close, less than 3 blocks away. While we could not check in early, we were allowed to leave our luggage at their restaurant, which was a convenience appreciated by these very jet lagged travelers. There were some restaurants closed because it was August - including what appeared to be a great Japanese restaurant and a creperie - as it was, we traveled just a little further for a crab restaurant. Yum!
In summary - Very good location, near the RER station - nice neighborhood convenient to most things. The 5 of us slept well and appreciated the well designed space.