Hi,
The aircraft should be a 747-400.
A seat map can be found here;
http://www.virgin-atlantic.com/our_s..._fleet.view.do
Fro the SFO route it will be the 747-400 (2).
You will have a PTV with a number of films;tv channels ( up to 20)video games and music.
A couple of aircraft have vport: ( Video on demand) with a CD Juke box of up to 50 CDs and 50 movies.
As for food;
Drinks service after take off
Choice of three main dishes ( one is a veg)
Ice cream during the second or so movie
snack prior to arrival
Free drinks during the flight.
Seating in Y is adequate ( unless you are tall) with about 31inches.
Hope this helps
Regards
TBS