I've stayed at both the JWM and the Plaza comparatively recently and the first thing you should know is that neither hotel is capable of heating their lobby!

The Plaza is in a good location but the rooms are painfully small - even if you do get a suite - and I wouldn't want to stay there for more than one or two nights.

The JWM is a nicer property but you need to make sure you get a high floor as otherwise you feel you're in a bit of a goldfish bowl on the street below. JWM also has much nicer lounge with a walk-out terrace. The kicker is the staff were unfriendly and unhelpful. After one night in a goldfish-bowl room, I had to push hard for an upgrade and was eventually given a sky suite - larger room with part of the windows extending across the ceiling.