Last night in Paris

I'm certain many of us could suggest a hotel for you but you need to tell us what you would like to pay.

Decide where to stay based on how easy it is to get to CDG, not only on the cost. I'd allow plenty of time to find the right airline counter and would arrive at CDG no later than 8.00 or 8.15. I have stayed at the airport the night before, just so I wouldnt have to get up as early, but that's the tradeoff.
If you stay near Luxembourg Gardens, the RER leaves directly for CDG, but that's not the only area with good train service.

I also would say stay at CDG. You need to be at the airport at least 2 hours early, We stayed at the IBIS at terminal 3. There is a quick shuttle to terminal 2 that leaves from the same station as the RER and is only about 200 feet from the hotel door. There are a number of other hotels near Terminal 3. You can always take the RER back to Paris for the last night.

I've stayed at the Holiday Inn @ CDG- look for their online rates, and package rates that include breakfast. They share a shuttle with several other hotels on one street. If you have never checked in at CDG, be aware that with most airlines, you will have to locate your flight and stand in that line, not the way it is in the U.S. where you locate the airline and stand in one line for all flights. Watch out for codeshares also - for example, you may have booked with Continental but United or Lufthansa are really operating the flight- etc.
In the mornings, CDG is very crowded, relax, go early and enjoy one more croissant after security, don't get flustered.

We elected to spend our last night in Paris rather than stay by the airport last year. We had a wonderful evening walking around the city. Staying at the airport is depressing to me. I would also suggest staying near Luxembourg Gardens. You can catch the RER train to CDG from there. We stayed at the Best Western Cluny. I would suggest getting on the train by 7:00. Yes, it's a little early, but you'll be sitting on a plane all day. CDG can be just hideous; I think it's best to try to be there 3 hours before your flight.

We once stayed at a decent small two star hotel just a block or so from the Luxembourg RER station on our last night in Paris. Not expensive, and it served its purpose of giving us a place to lay our heads. As I recall, a double was less than €100.

Sorry about that, I stupidly forgot to give you the name of the hotel or the link. It is the Hotel de Brasil, and the link is
http://www.bresil-paris-hotel.com/

Irv is dead on. We stayed at a hotel basically attached to terminal 3 but spent our last night wandering at Sacre Couer. Our memories of that September night are among the best of our lives. Our memories of the wasted time, long unmoving lines, and French inefficiencies at CDG the next ( final) morning made us glad we were there in PLENTY of time. The RER gets you to/from Paris easily the night before but maybe not such a sure thing when you absolutely need it to be.

I prefer taking the Air France bus to the airport rather than the train. For my upcoming june trip I am staying at the LeMeridian Etiole and the AF bus stops across the street from the hotel. Just a 35 minute ride to the airport and they load your luggage for you. I usually buy a round trip ticket which saves a few euros.