Watch out for those lifts - they break often! I was stranded in one for 35 minutes on Nov. 4th, fortunately having just arrived at Heathrow rather than having a plane to catch. Plenty of air, 9 other people to talk to, and a bloke on the intercom who kept reassuring us that someone would be there "soon" to free us. Use the escalators if you can manage it. You can leave your luggage cart and one end and find another when you get off.

When I got out I asked the Heathrow Express person for free tickets as compensation. She said "sure!" and gave me one free ride plus one free upgrade to first. IMHO, first is nice but definitely not worth the £10 extra cost. It's not like they give you a cup of tea or anything. Standard class, though, is now the best way to get to London.

As for the Hilton bridge - about a quarter mile, flat, free luggage carts at both ends. Great place to stay if you have an early morning flight from T4. Pretty nice otherwise too. Not as good if you have a car, since the lot is run by a separate firm & is expensive, probably to keep airport parkers from filling it. Avoid the Brasserie restaurant - they think they serve fine continental food, but the chefs aren't up to it.