Most of the FAs migrate up front to assist the First Class (and Business Class on three-class aircraft) cabin and passengers.
On SFO-ORD-SFO flights (two-class 767s and 777s) I have enjoyed the service of up to six FAs. I assume a number of them are from the Economy Cabin.
I was fortunate on my SFO-JFK R/T in that I was in 15B so I was assisted by the Business Class FAs from the BC galley located to my right who made sure I was well taken care of when the Economy Class FAs were doing food / drink service farther back.
[This message has been edited by SEA_Tigger (edited 04-21-2003).]