Back in 2000, I stayed at the Hilton Paris Orly and commuted into Paris for sightseeing everyday.
The one thing I remember about it 5 years later is that by taking the subway, I couldn't see Paris. It took something like 45 minutes or an hour each way, and all I saw was subway tunnels that look like any other subway in the world.
Hiltons in Paris either cost a lot of reward points or lots of cash (especially with the high Euro vs. dollar). That is why I chose the Hilton Orly (less points needed). The hotel itself is fine, but the commute stinks.
If you are choosing between hotels at the 2 main airports, then I would pick the one with the best above ground train service into Paris.
Hope that helps.
