As everyone says, JFK is notoriously bad because of it's predominant role as a transatlantic gateway. Lots of inbounds mid-afternoon, lots of outbounds late-afternoon and early evening. It's noticeable that UA heavily pad their JFK-LAX/SFO flight times during the periods of worst congestion.
The killer on VS flights is that the IFE is usually off, the crew are seated early in the taxi (which prevents them from doing even water/soft drink runs), and in theory you shouldn't use any PEDs (which rules out iPods, laptops and portable video players).
If VS would get their IFE certified by the CAA for non-stop use, then it would provide some much needed relief during such lengthy ground delays.
EWR, BOS or even IAD (depending where you're starting out from) are much better bets from that corner of the US - e.g. last time I was in PHL, I just took Amtrak up to EWR for VS2. If you're in New England, even just over in Southern CT, you may be better off out of BOS.
Having said that, I've been stuck in a 90 minute ground stop in IAD before now, on UA, however, as we weren't taxiing but were parked in a 'penalty box', the engines were shut down, IFE turned on, and dinner served.
Mike
