Can I suggest that you book in the LD instead of the UD on the 747? I found the LD to be much more comfortable since there's more pitch. On the UD if you're a window seat, it's quite difficult to step over the person in the aisle seat if you want to get out and use the lav or walk around. (There's not that much room between the middle console and the AVOD screen.)

As with everyone else on this thread so far, I'd go the BOS-ORD route. It's more direct and you'll like the C layflat seat. I've never been in F on an intl 777, but I'm venturing to guess the new C seat is much more comfortable.