I have no experience with either the Green Park or the Metropole but I do with Hyde Park.
Occasionally, my husband and I like to go to London for the weekend. I found this incredible package on site 59. Having never used this service before I was convinced that whatever hotel they were including in my package must be less than desirable considering the price. The CSR at Site 59 said that many people don't even bother staying at the hotel but just take the package for the savings. I decided, to be on the safe side, I would make a reservation at the Hilton at Hyde Park.
After arriving at Heathrow my husband and I decided to stop by the hotel included in our package. We were curious as to its quality, location etc. We thought this would be a good way to judge the true value of one of these packages, as well as the quality of the accommodations they offer. Although on the outskirts of London, we were pleasantly surprised when we saw the area in which the hotel was located. Trees and beautiful flowers lined the streets. The hotel was your typical moderately priced European hotel. The room had a queen bed and sofa. The hall leading to the bath had coffee pot etc. The bathroom actually appeared to have been recently renovated with wonderful tiles. We decide that if we were to book another package with site59 next time we would try their accommodations.
We head off to the Hilton at Hyde Park. I'm thinking this should be a really nice weekend. I am staying at a Hilton, I am one of their Diamond members so I am quite sure we will be in for a treat. WRONG!! They have us booked in a single room (even though the Diamond desk made our reservation). I show them my confirmation and ask them to call the Diamond desk if they like. He begrudgingly offers us a room with two twin beds. I say, I think not. Finally he gives us a room with a double bed. I notice that there are no breakfast coupons in the folder. When I ask if we will need these for breakfast we are told that he has already given us a 'double, double upgrade' what ever that means, and thus we are not entitled to breakfast coupons. After another rather unpleasant exchange we finally receive our breakfast vouchers. Finally... we head to the room tired and ready for a quick nap before we head out for dinner. I open the door to the room, and could not believe my eyes. This room was half the size of the previous hotel, no sofa. There was hardly enough room to even walk around the bed. Having had quite enough we decided to go back downstairs and checkout. I would never ever even consider trying this hotel again. I realize that we may have just visited them on a bad day, but that day was as bad as it gets as far as I'm concerned.
We went back to our original hotel. Found an absolutely wonderful restaurant, which also happened to be extremely reasonable all within walking distance of the hotel. No thanks to the Hilton at Hyde Park, we did manage to have a wonderful weekend in London.
So, my advise would be to stay clear of Hyde Park.
Good luck with your selection, and have a great time in London.