A Heathrow Express Train journey takes 15 minutes between London Paddington and Terminals 2 & 3, and an additional 6 minutes to Terminal 5. Heathrow Express trains stop at Terminals 2 & 3 and Terminal 5. Passengers travelling to Terminal 4 should change to the free transfer service (departing every 15 minutes) from Heathrow Terminals 2 & 3, adding an additional 4 minutes to the journey time in total. All Heathrow Express trains come equipped with at-seat power stations, free WIFI and luggage racks as standard.
I started in New England, went over to Chicago, down to Austin, and then spent weeks going from Austin to LA to San Francisco to Portland and finally to Seattle. It was one of the greatest trips ever. I took the train you were talking about with the observation room, and had one of the best dinners of my life with 3 other strangers in the dining car (all of us were traveling alone, and they seat singles together at one table). Three of us were young college kids, and then an older gentleman. We talked for hours- about youth, the world, everything.