Paris is truly one of the most special cities of the world and I recommend everyone visit this great city at least once. Here are a couple of my recommendations on a Parisian vacation.
A vacation rental is definitely less expensive then a hotel and can often be incredibly luxurious at a great value. I would recommend staying in a hotel for a few days when you first arrive then moving to a vacation rental. Sometimes rentals are very different in person then what you find in the photos. If you start out in a hotel you have many more options. This is the area of the city I would recommend staying if you get a vacation rental (touristy locations nearby, safe and generally nicer places). If you choose a rental that is on the 6th floor of a building, make sure they have an elevator and also look to see if there's a fire escape.
I really like this hotel because it is situated in a typical Parisian neighborhood (it is a business hotel mostly). It is a bit of a walk to tourist locations but it is an easy hotel to deal with, affordable and very clean/nice. The breakfast is excellent (generally comes with your room). The front desk staff speaks excellent English also. Oh and on Sundays there's a really deluxe outdoor market right outside the hotel (incredible fresh cheese and chocolate).
This is an obscure chocolatier on a very cute street. He's an excellent chocolatier that specializes in fresh cream chocolates for his local neighborhood. His prices are reasonable, yet he is one of the best in Paris.
Please let me know about your trip and share with us how it goes.