JohnEW, I am leaning more now towards just staying in London and traveling to Windsor from there. Then the family can take the tube to the airport or a taxi if that's what they want and then we could I suppose go to Paddington and take the train to wherever we decide. I will have to start to look at car rental soon. Not enough hours in the day.

Their best options to LHR would be the 1) Tube (fine or not depending on from which station) 2) The Elizabeth Line (great but again depends on from where), and 3) a pre-booked car service like justairports https://www.justairports.com

A taxi would cost an utter fortune

For a rental car start out checking Auto Europe. They are a broker based in Maine and deall with all the main players. They've been arounf for decades and offer terrific customer service (and are usually the cheapest - though not always)

. . . OR did you mean the family would be traveling from Windsor to LHR?? Then a taxi would be best. There are local buses too but tougher with luggage.

no, I think we will just stay in London and do Windsor as a day trip rather than trying to check in luggage early and changing hotels for only 1 night. So they would travel from Cidadine Trafalgar to Heathrow the morning of Friday, March 20th for a 12:25 flight. We will probably take at train from Citadin Trafalgar to either Devon or Cornwall and then rent a car( I will check out Auto Europe)

From that hotel I'd suggest a car service out to LHR. The only fly in the ointment is that its during congestion charge time (a Friday morning) so it will cost an extra £15 (total - not per person)

Or - They can do the very short walk over to Embankment station, catch a west bound District line train and do the easy transfer to the Piccadilly line at either Barons Court or Hammersmith. Biggest problem would be the stairs at Embankment.

I just looked at justairports and it seemslike a good value. I had to select a location, is Citadin Trafalgar 18-21 N Cumberland considered Central London

>>is Citadin Trafalgar 18-21 N Cumberland considered Central London<<

You need to specify your pick-up or drop-off area based on the first 3 letters of the address's zip code. The hotel's zip code is London WC2N 5EA, so you'd select "WC2-Central London" from the dropdown list

I booked a transfer through JustAirports.com this summer. It was convenient and a good value. Thanks to janisj, who often touts this company.

Reading54 is correct -- post codes (not 'zip' codes - that's a US thing) are your friend. Justairports wants the characters before the space to identify the neighborhood and calculate the fare. Then they'll need the full post code to know the specific pick up location. Street address are essentially unnecessary

You have each been SO helpful, I feel as though you either live in London or visit there often.

I think you have a great plan in place now - just doing Windsor as a day trip from London. BUT if you really wanted to stay at a hotel out there, you could choose one of the Heathrow hotels that are closest to the castle - like Sofitel or Hilton London Heathrow - which would almost definitely let you store your bags with them until checkout time. So you drop off your bags, then take a 15-20 minute cab to the castle, spend the day there, then back to the hotel at night.

Not necessarily recommending this as I think with your full group it might be easier to switch hotels the least amount of times, but if being at Heathrow already that night makes things easier, this is one option.