UA 777s occasionally get used on this route in the winter, but only rarely. In the summer count on 744s with both LH
As to the choice of airlines, I have three words for you: United, United, United. They are not what they used to be, but Lufthansa is so much worse, it doesn't even compare. Plus, UA
has channel 9 and so you will be able to listen to live air traffic control during the flight. No in-seat video on either plane though - sorry!
May I suggest that you try to connect in ORD
? That would give you the choice of 744, 777 or 767 for the transatlantic. 767 and 777 have in-seat video in Economy as well and they also have slightly wider seats (by about 3/4 inches or almost 2 cm). Keep in mind though, that airlines will sometimes change the aircraft type on short notice.
Also, if you look for good prices, you may consider US. Still Star Alliance and a great inflight entertainment system (you can pause, rewind and forward any movie whenever you like). No channel nine though and also only the IMHO boring and certainly tighter 330. You'd connect through PHL
Edit: OK, so far it looks like they might use a 777 on one flight FRA-SFO. I missed that one. It is a very late fight though, so you may prefer flying earlier in the day.
[Edited 2006-11-23 16:11:09]