The Marriott is centrally located in a very high rise tower. The lobby and 2nd floor restaurant are very spacious, perhaps a bit reminiscent of Communist times. Guest rooms start at the 22nd floor and go up to 40, where there is a roof top bar (that I never went to). But given all the distance to cover, sometimes the wait for the elevator was a bit exasperating. Oh yes, one of the six lifts always refused to take my key card, whilst the other five were just fine with it.
The executive lounge is on the 38th floor and they serve (1730-1930) "nibbles" that are unabashedly "dinner". Wine available 1730 until about 2100 or so. Snacks, cakes, sweets, coffee, soft drinks, mineral water available all day. I was quite pleased with it all.
The breakfast buffet was also very good. The chap on the egg station knew his stuff; the coffee was good, and the eggs Benedict superb. Also, they understand CRISP bacon. Brits may not appreciate that but we north Americans do indeed.
There were always properly licensed city cabs available.
I found my "standard" room to be comfortable, but not huge. My "life platinum" colleague had a much larger room and bath, so if you go premium, you'll be happy. I think we both agreed that perhaps the rooms were a bit "tired", but that is just a quibble. The water was hot, the shower wonderful, the towels good. He had a snazzy robe, but not I. Oh well.
The internet service was blazing -- my e-replica, 100 page newspaper would download in (literally) five seconds. Never went down; did not need to log in constantly. Great, great stuff.
Darn fine option in central Warsaw.