Starwood does not have a large footprint in the UK. Marriott is much larger here and so should absorb the Sheraton's 11 properties pretty easily. It does mean that the new company owns 5 hotels at Heathrow (Marriott's - Slough/Heathrow, Renaissance Heathrow, Sheraton Skyline and Heathrow), The full list is of Starwood properties in the UK is: England Hayes Sheraton Skyline Hotel London Heathrow Liverpool Aloft Liverpool London Aloft London Excel London Aloft London Tobacco Dock - Opening September, 2017 London Element London Tobacco Dock - Opening September, 2017 London Great Northern Hotel, a Tribute Portfolio Hotel, London - Opened September 9, 2015 London Le Méridien Piccadilly London The Park Lane Hotel, London London The Park Tower Knightsbridge, a Luxury Collection Hotel, London London W London - Leicester Square West Drayton Sheraton Heathrow Hotel Scotland Ayrshire Trump Turnberry, a Luxury Collection Resort, Scotland Edinburgh Sheraton Grand Hotel & Spa, Edinburgh
I used to be Marriott guy. My local boozer was the bar at the Marina Del Rey Marriott in California. When I returned to the UK, the average Marriott price was always substantially more than the neighbouring Hilton or Holiday Inn. The amount of work that you need to put in to maintain status is crazy (although I have had some worthwhile challenges). I think the takeover of SPG will just drive my SPG business to HHonors or IHG.
The FAQ for the 'Marriott Experiences Marketplace' says that the program merger won't happen until 2018. So we have at least two years left! https://www.experiencesmarketplace.com/page/content/help