I am looking at flying to London from Chicago.

3 options are..

United on 767-300
Virgin on A340
British Air on 777

Which would have the better coach seating? Is the upgrade to Economy Plus or a similar plan (World Traveler Plus on BA/Premium Economy on Virgin) worth it? Two kids (9 and 8 yrs old) might be coming...does that change the upgrade value?

Also... I might have to fly direct on the way back from LHR to SFO. Aer Lingus is by far the cheapest way to go with one stop. How is their A330 service?

Thanks!