I've stayed there about 5 times and been upgraded to a suite every time. Whilst not amazing suites, if you get one opposite Green Park, they're pretty spacious for London and I've always found them very comfortable/clean. The hotel location is great too. Your profile doesn't say if you're a Plat or not Corky so that will obviously be a key influencer for an upgrade.

Not stayed at the W yet so can't comment but if you do bag a suite, it's a better upgrade than at the Park Tower for example and at a cheaper cash/points rate.