Flight
Heathrow is usually the best airport for first-timers into London, as it has an easy (and cheap!) connection into the city via the Piccadilly line. *NOTE: We suggest avoiding the Heathrow Express trains unless you have a ton of luggage and/or you need guaranteed seating. It's pretty much the Piccadilly line, just with slightly more luggage space, at about five times the price.
Flight
Kayak searches all sites at once, and also suggests when it's best to buy. I've used it personally in the past and haven't yet had a problem with it.
Train
We suggest finding hotels or Airbnbs close to stations on this line (especially if you're flying into Heathrow). *If you're coming in on the Piccadilly line and need to switch to District Line to get to your hotel, we suggest doing so at Baron's Court. Both District and Piccadilly Eastbound trains are on the same platform here. Best combo neighbourhoods/Piccadilly line stations include: -Earl’s Court -Hammersmith -Baron’s Court -Gloucester Road -Green Park -South Kensington -Knightsbridge -Hyde Park Corner -Leicester Square -Covent Garden -Non-central (also cheaper) good areas: -Boston Manor -Chiswick -Gunnersbury
Hotel
Extremely luxe central hotel, this is where Sarah and family will be staying. Please book in advance as this hotel fills up, and prices also rise closer to the date.
Hotel
Nice hotel with good connections to the city. District Line is just a couple minutes' walk away.
Travel Note
There are currently some good deals on Airbnb, but these book fast. Try to make sure your room or apartment is within 10 minutes' walk to the nearest station. Best neighbourhoods include: -Earl’s Court -Hammersmith -Green Park -South Kensington -Victoria -Oxford Circus -Bond Street -Ealing Broadway -Chiswick -Gunnersbury