Layovers in London

1st layover- 7 1/2 hours is not as long as it seems. It will take about an hour maybe a bit more to clear immigration- a bit more if you must get luggage and re-check it for your next flight (only necessary if you did not book flights together through one airline). Then, you MUST be back at airport 2 to 3 hours ahead of flight- for check, in security, etc. Heathrow is infamous for long lines. That cuts you down to about 3 hours. You have time- maybe- to take bus or taxi to Windsor and have a look around, maybe eat a meal. Probably not enough time to tour the castle. This is assuming you flight landed on time. Getting into London itself takes about 20 min. on the Heathrow express or and hour on the tube. Then you have to get to what you want to see- not enough time for hop on/off bus, and need at least as much time to return and check in again- security etc.

Either plan on "seeing" the town of Windsor or doing some resting and window shopping at Heathrow. The do have extensive shopping - Harrod's has a branch and LOTS of other shops, too. There are lounges you can pay to use- quiet, rest, watch TV, even shower. If you have elite status with Frequent Flyer miles, many of the airlines have VERY NICE lounges.

Layover 2- You will probably have to claim your bags since you have an overnight layover. That makes London your "final" destination for that day. Allow plenty of time to check in for your return flight.

It would be better if you planned on going to Windsor, which is a 15 minute taxi ride from the airport. You would have time to visit the castle, walk to Eton (5 minute walk), walk to Windsor Great Park (5 minute walk) and have a pub meal.

If you decide to have a VERY QUICK visit to central London, don't waste your money on the Heathrow Express. Paddington station isn't close to any tourist sights so you'll need to take the Tube or a taxi to get to them. And you'll only save about 15 minutes compared to taking the Tube all the way from Heathrow.

My suggestion would be to take the Tube (Piccadilly Line) from Heathrow to Hammersmith. Walk from one side of the platform to the other and take the District Line to Westminster. You'll emerge right by Parliament and Westminster Abbey. Take a walk toward Trafalgar Square. Take the Tube back to Heathrow. (Allow an hour to get back to the airport.)

After saying all that, you'll be much less rushed if you do what others have suggested and visit Windsor.

We had a layover in London on our way to Rome in 2008 and we needed every bit of it. It is a big big airport and it seemed like first we were on a bus for quite a while, and then we walked for hours to get to the connection, not to mention immigration. I don't have a stomach for rushing in airports, but if you do you could certainly try it.

If you decide to go for it, be prepared to pay for a taxi back if there are problems on the tube. It only takes a signal failure or leaf on the track and you can be stuck.

One would not ask how a leaf.......okay, I'll ask. How?

Answering the last part of your original question - on your return, if you check bags, then yes, the airline will keep your bags. Most airlines will not let you check your bags to an intermediate stop over point even if overnighting. This actually works out really well since you are not burdened with heavy bags. Just remember to keep a small carry on with the stuff you need for that one night and the next days flight home.

We've got a five hour layover at LHR in May. Has anyone bought a pass to the Servisair Terminal 3 lounge?

Is it worth the $50 or is it just as mad as the regular terminal?

look it up... leaves on the line is a serious issue and much joked about here but it is true.

When sap from the leaves attaches to the rails, it causes serious traction and braking problems.

leaves on the line are only a problem when they are falling in the autumn....

did have the wrong kind of snow causing havoc not to long ago, and Eurostar was frustrated by the wrong amount of cold in the tunnel......

I had a similar lay over many years ago; on a Sunday. I went by underground to the V&A, had a few hours there and then took the underground back. (not aware of the train stopping leaves) I timed the ride from the airport to the museum and allowed the same time for the ride back. Since it was a Sunday I did not have a wide choice of museums that opened early enough to let me have a reasonable visit. I did have to pass through immigration and customs leaving the airport and returning for my connecting flight. Also, I had to be back two hours before my connection. That 7 1/2 hour lay over can evaporate quickly...