Originally Posted by
canadou
Best piece of advise I could give you is DO NOT MAKE INBOUND STOPOVERS unless you have 5 or 6 hours of layout.
Great - thanks
canadou 
I've got 6 hours between my LHR-SFO and SFO-JFK flights, so depending on how quickly I get out of the airport I might hotfoot it downtown for dinner as it's only 30mins on the BART.
Originally Posted by
Blueboys999
I have done similar in that time and also had it take much longer. The traffic is brutal between JFK & LGA at that time of day.
It can be done but isn't something I'd feel confident about if it was me.
Thanks for the advice
Blueboys999, there're lots of flights out to ORD from NYC so I'll stick an extra hour in-between landing at JFK and departing from LGA, hopefully on a Sunday morning that'll give me enough time to transfer.