I am currently at the Westin Warsaw (checked out of the Sheraton this am), and am very happy. I was here 2 years ago, just after they opened and at that time, no suties or executive lounge was available). This time on a very (for me cheap rate of e76 rate), I was pre assigned a suite on the Executive floor. I will post some pics when I get home, but it is a 2 room suite with 1 1/2 baths. The Lounge (where I am sending this from) is also very modern, with a good selection of 'beverages' and food-- although I must say, the Sheraton's spread is bigger and more varied. Then again, it is almost 7pm on a Sunday evening and I am the one and only occupant at the Lounge--(all that booze and just me ) The staff is SOOOOOOO nice, as I am sitting here with my 1/3 left of a glass of Prosecco, and the attendant came by to refill me !! ) She also asked if she could bring me anything from the food selection-- How Nice!
So from my perspective, it is a toss up between the Sheraton & the Westin.
Sheraton- Food & Beverage selection absolutely fantastic, room / suite- ok, but not great, lots of restaurants in hotel, staff very good and close walk to main area of city.
Westin- Great upgrade (a month before arrival to a real 2 room suite !!), modern, good staff, lounge good, but food & presentation (IMO) better at Sheraton. Close to Old Jewish Quarter, but a walk to other areas.
In Sum- coming back, I would again do both hotels (one night each Sheraton & Westin, as for the Bristol-- it seems close to the Old Quarter--

OPPS, here she comes again--- guess I have to stop for some more Prosecco! Perhaps I shouldn't promote this place so much, it's great being the only one here!

PS-- Here are some pics:
http://www1.snapfish.com/share/p=555...c=SYE/otsi=SAL