Hi Hilary
We did this at Christmas time and I was a nervous wreck beforehand, being our first time. We originally had two and ahalf hours to change at Newark but then Continental changed our flights leaving us an hour and three quarters. We checked in at Bristol and were given boarding cards for the Bristol to Newark and Newark to Orlando sections of the journey. The flight from Bristol to Newark was brilliant, excellent entertainment system, good food and very friendly air hostesses. We landed in Newark off the plane and through immigration, we then had to collect our luggage - this was just around the corner from immigration, take our cases to baggage drop off again really close to baggage pick up, and there were Contnental staff there asking where you were going to make sure that your cases went off down the conveyor, it was at this point they started fussing us saying we had to hurry, we knew that as we didnt have enough of a stopover IMHO. We then had to catch the trolley airbus thing (monorail) to the other terminal, and pass through security, showing our passports, boarding cards, and make our way to the gate which typically was the furtheat one away. We practically ran through all the gates, when we got there we found they hadnt even started boarding as the plane was delayed half an hour. When we did board the captain announced that they would be waiting another twenty minutes for some connecting passengers.. We arrived in Orlando after a short two hour flight where we were served drinks, and then came off the plane straight into arrivals and baggage claim, no need for immigration, which was wonderful. I would definately do it again, but would insist that I needed more time for the stopover.
Hope this helps xx