Someone recently asked me about this and as I know a few other people who are heading to France in the not too distant future I thought that might be useful to share some experiences of appartement accommodation here.
Ursula and I spent 7 wonderful weeks in Europe last year and in all we had 5 separate appartements in different countries including 3 in France. These were 1 at Nice, 1 in the Perigord and 1 in Paris.
Taking an appartement rather than a hotel room makes a lot of sense. Its generally cheaper plus you can self cater. Anyone who has had to live out of a suitcase in a hotel room for any length of time will verify that this is an experience that will soon make you homesick! And even with the best cuisine in the world at your disposal, eating out for every meal soon loses its appeal, even without consideringthe expense involved.

In your apartement you will feel you have a home away from home and preparing simple dishes made with the fresh ingredients that you have purchased that afternoon at the local market can be a lot of fun.
The only downside is that generally you must rent for a minimum of 1 week which is obviously less flexible.
We booked all 5 of our appartements in advance ourselves using the internet and found this to be a very satisfactory way to go about it.

The web site that we used is http://www.homelidays.com/
and we liked it because it seemed to have the biggest range of choices and was very easy to use.
You simply select your region of choice, in the case of Paris this can be narrowed down to arrondissement, set your price range and how many bedrooms and so on.
Each appartement listed has photos of the rooms, and a calendar of availability and other details but most importantly there are testimonials of other previous renters. These testimonials help you to find the absolute best places and avoid the more dubious ones. We were absolutely delighted with all 3 of the appartements that we rented in France.

As you must deal with the individual property owner, and they sometimes do not speak much English, the minor hassle that we found was arranging for a deposit to be paid in advance from Australia.
Having said that we found the people that we dealt with to be very helpful which was not surprising really since we looked for this particularly in the testimonials.

In Paris we stayed in the cosmopolitan 10ieme arrondissement. The appartement was beautifully appointed spacious and in a very quiet (important!) courtyard in this busy part of the city.
We would have preferred the quartier latin or montmarte but could find anything suitable there, (we needed 2 bedrooms as there were 3 of us), and also we were attempting to book "only" 4 months in advance.

Wherever you do choose to stay, try to avoid anything above the second floor if there is no lift, unless you want to get very fit! and avoid the top (usually 6th) floor as these appartements become very hot in warm weather and finally book as early as possible to get the best choice.

And a last word on the important topic of food!
Don't forget to try to squeeze in to the lovely old Bouillon Chartier on the rue Faubourg de Montmarte.
Bouillon Chartier
Some Parisiens turn their noses up at the basic regional cuisine on offer but of course that doesn't mean the food isn't very good and everyone loves the ambience. When you walk through the swing doors you enter a belle époque dining room which has hardly changed since 1896 you feel like you have gone back in time.
Somewhat surprisinly it is relatively inexpensive but you can't book a table and to avoid having to queue it's best to dine early.

And if you have a sweet tooth you should give yourself a treat and visit at Angelique's Salon de Thé on the rue de Rivoli a stone's throw from la Place de la Concorde. There you will discover the best hot chocolate in Paris and even the Parisiens agree with me on this!
Angelinas