I spent 3 nights at the JW a few weeks ago. No issues with air quality in the city at all - not sure if I just lucked out. I concur that the location is good - although just note that the closest subway station is still about a 7 or 8 minute walk away (still close, but it's not like it's connected to the hotel).

I wasn't as blown away by the food selection in the lounge (see pic), but perhaps I've just been spoiled by other lounges in China (such as the club lounge at the Renaissance in Beijing). First world problems: the lounge had no Diet Coke/Pepsi (not sure if they never carry it, or if it was just for those few days). And there was no Family Mart or 7-11 super close by (closest I found was about a 10 minute walk away).

But those are minor quibbles. The JW is a great property and I would not hesitate to stay there again. And we were pleasantly surprised by Hangzhou itself. The West Lake area is as nice as they say!

And for a surreal experience, be sure to take the city bus out to Tianducheng for a view of the fake Eiffel Tower. (It's possible that by next year the subway out there will be open making it even easier to get to!)