My girlfriend definitely likes to be licked, but I usually don't let her finish when I am doing it. You know how long that takes and besides I rather warm her up for the real action.
Depends on the girl. If you have one of those girls where you have to pound her pussy for 30 hard minutes to get her off, then ya.
My girl usually cums 2-3 times each session, so its pretty easy to give her the 1st one orally. I like to do that so if we dont have a lot of time I dont have to worry about finishing fast and robbing her of hers.