I don't know, but hopefully someone will.

Ooooooh, I spoke too quickly...my BFF stayed in the Hilton.
She used that as a base to go to Windsor.
She loved the Japanese restaurant there.
Hope that helps.

Thank you, Judy. I am looking at the Marriott Renaissance and Heathrow Airport Marriott as well as the Hilton Heathrow and Hilton Heathrow Terminal 5.

Do they all take the same level of points? If so, your decision should be based on which terminal you are using. One hilton is AT terminal 4, one hilton is near but not at terminal 5, the Marriotts are convenient for T-1, 2, 3.

I'll be arriving on Air Canada which I believe is Terminal 3. The hotels are the same amount of points.

Then choose one of the Marriotts - the Hilton are not near/convenient to T-3.

Both Marriotts are on the Bath Road just off the north side of the airport

Would you say they are both comparable?

I haven't stayed in either one but have been in lobbies/lounges both of both. Not a lot of difference quality-wise. 6 of 1/half dozen of the other really. At least in the bits I've seen. Nice airport/business hotels.

The Marriott Heathrow is a newer modern style hotel and was opened not that long ago, it's a striking building with lots of glass; the Marriott Renaissance has been there for years and was previously the Penta, more old fashioned exterior but good views of the runway, as it is on the opposite side of the road to the Renaissance (if you get a room on the runway side). It doesn't make much difference, but personally I would take the Marriott Heathrow.

Why *must* you have a hotel room at Heathrow?

There might be a case if you have an extremely late arriving flight to London or a very early morning flight from Heathrow but in both cases I'd organise a car service.

The only exception is if I wasn't travelling through London itself but arriving or leaving for some other part of the UK.

But then I'd consider staying in Windsor overnight and using a Windsor based taxi company between it and Heathrow (Note the Marriott "Windsor" ISN'T in Windsor, they've obviously had an attack of Ryanairitis.

alan I don't know about OP, but I usually stay at a Heathrow hotel because I can never make it back from France, Spain, Italy, etc. in time for my Virgin flight to SF. There is only one flight a day; and I fly Virgin as I have mega miles that permit me to fly Upper Class.