As far as entering the USA is concerned, try to avoid DFW; its simply atrocious. There seem to be never more than 3 “alien” channels open and even arriving F or J, you will always tag onto the end of a queue from a Chinese airline’s A380!! There are constantly girls calling out connecting internal flight passengers to come forward and queue jump, lest the departing flight be held up (or you miss it and the airport will fill up with disgruntled passengers). The border staff roster “manager” needs to be replaced.
In any event, if you want to have just one quick drink of anything, leave yourself 4 hours transit in the USA – immigration queues, terminal changes, collecting and re-checking baggage, custom exit queues…….then you don’t have to fret in each queue!
Another tip for those travelling as a family group – when entering the USA and using the auto passport readers to get your slip to show to the border chaps, make sure you scan the named party lead first – otherwise you get nowhere as the subsequent passports are rejected!!