At W hotels, at least from my experience, there is a qualitative difference between spectacular and wonderful rooms. Spectaculars are either bigger, better view, etc. than Wonderful. At W City Center, my experience is that Spectaculars are less likley to face the street, more likely bigger, and so on. I am only gold, but they upgraded me to spectacular every time I stayed there (must be three or four times now in the last nine months). Besides, their Wonderfuls are pretty good anyhow. (As an aside, they have few if any Spectaculars that are non-smoking with 2 doubles, so if that's what you want, you might not get upgraded to it and would be better off paying the extra for one). For my money, I'd just go with Wonderful and hope for an upgrade especially since you are PLT.
I am surprised there are no better deals at W City Center, though. I've never paid anywhere close to $200 a night there....

You mentioned W Chicago. If you are referring to W Lakeshore, Wonderful is city view (ie no view), and Spectacular is Lake view. As a gold, I got upgraded to Spect each time as well. So I'd save my money there too.

Have fun!