It seems some of the terminals have good sleeping area in Paris CDG airport. My arrival and departure terminals may be different. Will I be allowed to go to a terminal where I want to spend my layover in as I wish? Or do I have to stick to my departure terminal?
When changing terminals at CDG, you would have to go through either a security check or passport control, or both. EasyCDG has a tool that guides you, and gives step-by-step directions.
You can identify your arrival and departure terminals. You can stay in the secure area of either of those terminals. If the area you want is in another terminal's secure area, you wouldn't be able to enter without having the correct boarding pass.