I am preparing to make reservations through Air France that will take me direct from Houston to Paris, and then make a connection to Istanbul with a one hour to catch that flight, also on AF. Is this enough time?

Turkey is not part of the EU, so do I have to go through customs in Paris and also when I arrive in Istanbul?

There is an alternate flight that would give me a three hour layover, but of course, if it is possible I would prefer to arrive earlier than later and start my vacation!

That sounds tight to me, if your flight from Houston is just a bit delayed you will be really rushing. I had a similar time between flights last year at CDG, 50 minutes to connect with a domestic AF flight to Nantes. I did lose my bag (only for 24 hours). On the other hand if you know there's a later flight you could just chance it.

Most European countries still have transit, unlike the US, so you don't need to go through customs if you are just passing through. More informed Fodorites will know if that's the case for France.

ttt

Your flight from Houston will arrive 2E. You take the airside bus, which will stop at 2C, 2A, and then 2B, where your flight to IST will depart. You don't have to go through immigration.

If you miss your connection, AF will put you on the next flight, assuming there are seats left on the later.

An hour is not enough time. Yes, AF likely would put you on the next flight, but the short connection and possible need to put you on the next flight significantly increases the chances that your luggage will get mislaid. Also, I'm not sure how fussy you are about seating, but if you could get stuck with a lousy seat (and it's a fairly long flight to IST) if you're delayed. Finally, there is the PITA factor of getting booked on the new flight, getting a new BP etc. I would take the flight with the 3 hour connection, if I were you.

Have you looked at flying with American and Turkish Airlines (AA to ORD then Turkish Airlines to Istanbul) instead? (You can collect AA miles with Turkish Airlines). I've flown Turkish Airlines about a dozen times in the last two years (Paris-Istanbul) and thought the quality and service levels were quite good. By contrast, I did fly Air France from Paris-Istanbul once and thought it was terrible: cramped seats, lousy food, limited service, etc.

Take the 3-hr layover flight.
Flew out of 2E this past Friday and
it is a nightmare w/the usual French
efficiency. Bus took forever to get to
plane & we sat and sat before boarding.
No telling when the 2E construction will be completed.