Just want to make sure you did not miss out on this. You don't happen to work for Oil&Gas Industry, do you? If you do, then you apply for Petroleum Club membership (FREE) and that way they will get you a room at Sofitel for free (during your 17 hrs transit) when flying on economy full fare, business class and first class.

If that is not the case, then there is definitely some lounges you can use when arriving CDG which also allow you to take a shower. They have a very strict policy that you cannot leave any carry on luggages behind though. If all the heavy bags are checked through, pack a small carry on and you MUST walk around Paris and spend your 17 hrs in the city. It is worth it. I had 15 hours transit before, and I definitely enjoyed my day in Paris. But I was lucky to get a room at Sofitel (through Petroleum Club).

It is quite easy to go around Paris from CDG these days even if you don't speak french. Check out AF wesbite, they even have a one day package for you. But if you know exaclty what you want to do, I would recommend to just do it on your own. If you come back early before catching that 11pm flight to BKK, take a short nap in the lounge, it is safe. Enjoy your day in Paris.