I understand it is best to layover in Europe on you trip TO Europe. What about the return flight - is it best to layover in Europe, the U.S., or it doesn't really matter? Thanks!
Personally, I'd prefer a US layover since missing the connection usually wouldn't mean a 24-hour delay in getting home, because there are so many more domestic flights available. However, so far I've always been stuck with connecting in Europe and have had no difficulties.
You'll normally need to allow time to clear immigration and customs at your US gateway, though.
In my opinion it is better to layover in Europe on trip over to Europe. By the same token, it is better to layover in the U.S. on the return trip. Simply put, if you miss a connection you are at least a lot closer to your final destination. In addition, you will have many more options for getting to the final destination.
Mrs.EB is right. It depends. A layover is a layover. It may be comforting to think, OK, I'm in the US, I'm a lot closer to home, there is another flight just around the corner. But, having lived through a UA nightmare in NY that lasted over 24 hours before getting on a plane to California, I'd say it didn't matter where I was, I just wanted to be home!
When I go to the US, I prefer a European layover. I don't want the hassle of passport control, waiting for luggage and clearing customs, rechecking luggage (if you can do it right there), then having to go from the int'l terminal to a domestic one to get my connecting flight. If I miss the connection (and I wouldn't choose a short connection), I figure the worst case is that I'm stuck in Europe for another day and the airline has to take care of me.
If you only have carry-on, it probably isn't as much of a hassle. But remember, you can't bring duty-free liquids back with you.