I did MEL-LAX-JFK with VA and DL three times last year (and am doing it again tomorrow). Each time a 2 hour connection has been plenty. The new photo/fingerprint kiosks at passport control seem to have sped things up considerably. As one of the other posters said, the biggest risk of delay is at the DL domestic security line where, for reasons I'll never understand, people seem to start the process of removing laptops, belts, shoes, coats etc. only after they are standing at the tubs/conveyor belt, despite numerous signs and TSA staff shouting instructions. To put it mildly, its a shambles. But, again as another poster mentioned, the relationship between VA and DL is solid and DL do go out of their way to assist VA guests (especially if you have status). Enjoy the trip!