I transit the USA at least every 6 weeks, some airports are certainly better and speedier than others but the whole experience is actually not that bad at all. Ensure you fill in the forms correctly, answer any questions and you will be fine. You reclaim and recheck your luggage at the first point of entry into the USA, this is usually well organised and the airlines take it from you as soon as you exit the arrivals hall(as long as it is tagged to final destination). Spent a month in Europe this summer which involved a lot of travel flying in and out of the UK. Passport control at LHR and check in at STN were probably more frustrating than arriving at a US airport, and i have a British passport! I usually like to allow 2 hours minimum between flights when transferring in the US if i have to clear immigration, but last week i arrived from London and had cleared in about 20 minutes, collected bags and was at gate for my next flight 45 minutes after gate arrival, it is not always that quick though.