Need help with public transportation for two trips

Best and lesast expensive are not necessialy the samne. The easy (and more expensive) way is to use the Heathrow Express and the Gatwick Express. Straight, non-stop journeys from the station to the airport (or vice-versa). There are also the Southern Trains (Gatwick) and Heahtrow Connect- slower and a bit cheaper. For Heathrow you can also use the tube- much slower (45min.-1 hr vs 15 for the Express) but also MUCH cheaper (4 pounds vs. alot more). We value the speed and the directness- so we have used the Express (both airports).

The fare for the Heathrow Express is £16.50 if you book your ticket in advance online and £18.00 if you buy it at Heathrow. The fare for the Heathrow Connect is £7.90. The current fare for a single ticket on the Tube for travel from zone 6 to zone 1 is £4.50. If you're packing light and can easily schlepp your luggage, the Tube works fine. Take the Piccadilly Line from Heathrow to Earl's Court. Transfer to the District Line and take it to Paddington. The standard fare for the Gatwick Express is £16.90 (10% less if you book online). The anytime fare for a Southern train is £11.90. Booked well in advance online at www.southernrailway.com, you can get a discount fare as low as £3.75, but you are locked into a specific departure date and time.

Gayle- THe Heathrow Express is nice-15 min direct fast train to Paddington. If you are buying a "Brit Rail" pass for your other travels (outside of London, it will cover the heathrow express. The tube is also an option. It is cheaper-but it can be slow and packed w/ passengers. You can buy a few types of tube passes. An Oyster card will allow you to pay for a direct fare. A travel card will give you unlimited tube access for the day. You can buy the pass in 1, 3, and 7 day. Here is the key: You most likely will only need a tube pass for Zone 1-2. To get from Heathrow to Paddington you will need a pass that will cover all zones. The passes are also cheaper after 9:30 am and condsidered "off-peak". I hope that helps!

I disagree with the frequent advice to just take the Tube from Heathrow. To me, both the Heathrow Express and the Gatwick Express are well worth the money. The Tube line out of Heathrow is the Piccadilly line. It does not go to Paddington. So, you'd need to change. "Light" luggage to me means something that fits in my lap. Traversing Tube stations typically involves a fair amount of walking and going up and down steps. Even a small rollaboard is going to be a real hassle. If it's rush hour, the Tube is going to be Standing Room Only. There's a reason they say "Mind the Gap." Some gaps are several inches wide, and several inches above the station floor. Then there's the ongoing series of more or less monthly 24-hour Tube strikes, during which you don't want to be anywhere near the place. Most important: Tube stations and Tube lines are often closed for repairs and service on weekends. That includes the Piccadilly Line servicing Heathrow. You're going to be doing this after a long overseas flight or at the end of your visit. Just spend the money and take the express. I was on it just a few days ago. Was in York until after 5pm. Took a train to King's Cross, a cab to Paddington, and the Express to Heathrow, arriving around 8:30.

If you travel from Heathrow to London by Tube (Tim above), change at Hammersmith- you just walk across the platform to get to the other train. If you wait until Earls Court the trains arrive at very different levels, need escalators or lifts (dont remember what they have)