In December I have a trip to Hong Kong in Y and my itinerary includes looong hours inside an airplane.. I have a short 1 hour flight from FLN-GRU then a 10 hour flight from GRU-DFW and then the 17hour AA flight from DFW-HKN. Connection times are about 3-4 hours..

Any tips on how to survive these flights?

I'd offer these tips:
* Try to plan in advance when during the flights you'll sleep and when you'll try to be awake. Optimally, you'll want to try to get it to coincide with the time of day in Hong Kong.

* If you haven't used sleeping pills before, get a prescription now and see how they work for you. Or try various over-the-counter remedies. You don't want to experiment with unfamiliar meds on a flight.

* It's worth paying extra for optimal seats. Optimal means different things for different people, but it's worth it if it enables you to have a more comfortable flight.

* Load up on book, movies, magazines or whatever you need to entertain yourself.

* It's been a long time since I've flown through DFW, but if there's a lounge with showers or a hotel with day rooms you should consider paying for access so you can shower and nap, if it's a convenient time for you to nap, or even get a workout in.

* I find that many airline meals are too high in carbs, sodium and fat. Consider packing some snacks, sliced fruit or even lean protein (poached, sliced chicken with a chutney is one of my favs) that you can eat while flying GRU to DFW. You'll want to eat any fresh food -- plant or meat materials -- before clearing customs and immigration at DFW, since that is a big no-no with customs. You can buy more food at the DFW airport to carry onto your HKG flight.

Welcome to FT!

I'm guessing you mean HKG, not HKN. HKN is Kimbe Field in Hoskins, Papua-New Guinea. I don't think anyone flies there nonstop from the other side of the Pacific.

One thing you might do is consider changing your routing to go connect in Santiago and Sydney. That cuts the longest leg to 14+ hours in the air.

Other than that, Ambien CR works for me. I don't use it on flights under 8 hours, because they don't give it enough time to wear off. Ask your doctor.

Welcome to Flyertalk, marcelo4527Talk to your doctor about compression stockings. That is a lot of sitting, unless you plan on walking around a lot. You don't want to be at risk for DVT. Drink a lot of water.

I think that's a great way to get a member of the Beagle Brigade come sit next to you should you forget to properly dispose before reaching DFW

If you just want a shower, it looks like Minute Suites offers one for $25 (up to 30 minutes).
http://minutesuites.com/pricing/

If you want a shower and full lounge experience, the Club at DFW charges a $50 fee.
http://www.theclubairportlounges.com/club-DFW.html

Both of the above are open to any passenger.

If you have an Amex card, $50 will get you into the Centurion lounge. It's often considered the best lounge in the US, though reports lately are that it can get crowded, so there might be a wait for the showers, or they may even turn you away.
http://thecenturionlounge.com/locations/DFW

Finally, assuming you're flying AA, there's the Admirals Club. Also $50 for a day pass, or $99 for a 30 day pass.

All of the above are found in Terminal D, which will be used for both your flights (since they are international).

Thank you for the suggestions! And yes I meant HKG.

I will probably try one of the lounges at DFW and hoppefully there will be wifi onboard for a reasonable price.

About the sleeping pills I'm not sure how it would work since I'll be coming from a night flight from GRU, unless I choose not to sleep on that flight and try to sleep on the DFW-HKG flight

This is a pretty rough itinerary. So bad that I wouldn't have booked it. I'd have broken this into two segments with 24-36 hours between the long legs.

Here are my recommendation:

- Sleep without aid if you can on GRU-DFW.

- On DFW->HKG At 2-3 hours in take 10mg of Ambien (prescription!). This would be right after they take away the plates for dinner. That should knock you cold for most of the trip.

- You won't feel very good on arrival at HKG. And drug assisted or not, make a mental note to yourself to count your luggage every time you move. My biggest travel mistakes occur on arrival, jet lagged and disoriented. On the plus side, you are arriving at HKG, one of the world's best airports.