6 hour layover in Heathrow

Not worth it. Getting off the plane and then out of the terminal takes a while. Then (if it's an international flight) you'd have to be back 3 hours before your flight to go thrugh security and passport control. That only leaves a couple of hours to get someplace, hang out, and then get back.

Not with only 6 hours. I'd just look for a good place in the airport to hole up and hide.

If you decide to go into London, the Heathrow Express into Paddington Station, takes about 15 minutes non-stop each way, at about $55 roundtrip. From my experience flying into Heathrow, boarding for connecting flights begin almost an hour before take-off, so factor that time into your plans. This week, we were told to be at the gate at 11:30 for a 12:25 flight. I have seen the gate close 30 minutes before departure.

If you stay at LHR, there is good duty free shopping, and a bunch of nice lunch spots, so things to keep you occupied. The AA lounge has plentiful food options and reading material, and the BA lounge has lots to read as well, with some lesser food options . If you have access to the BA Fist class lounge, there is a massage therapist you can reserve an appointment with.

Some info on Heathrow layovers from another travel forum:
https://www.tripadvisor.co.uk/Travel-g186338-c195392/London:United-Kingdom:Heathrow.Layover.Central.London.html

6 hours isn't enough, you'd basically have enough time to get into the city and then turn around and get back. You don't want to miss a transatlantic flight.

I did find the prices at one of the airport bars to be exactly comparable to London prices. I vaguely remember the food prices looked to be about the same as well, so if you're stuck at the airport, at least it won't be a total ripoff. London prices are expensive, of course, and the Pound has been strengthening. I didn't really look at the prices in the stores as all I bought was a newspaper and a couple of magazines.

This is great advice. Thanks