I stayed at the W downtown recently. Can't speak for the suites but compared with the Andaz 5th ave, (where I did get a suite) its - well there's no comparison. The Andaz has a very sophisticated and sleek feel. All amenities are free, except alcoholic beverages. Wifi is free too, which means you are getting premium benefits even without being a plat/diamond member.
At the W a bag of chips will cost a fortune. Uptown is also much more elegant and clean, while the W overlooks the WTC which is fantastic, if you get a room on that side. It's a construction zone and the streets are dirtier.
Our suite at the andaz came with a dishwasher! It was spacious (btw it was a free upgrade) light and roomy. The room at the W was very tight.
The one advantage of the W was the amazing Bliss spa soaps. If you end up there get as many as you can. I just ordered a full size facewash after trying it out there and it cost $30 on sale!