Band 2 most exciting for me, only because no leaks and the most to improve upon.
SP4 has to be equal weight to Surface (Atom) 3 before I'm interested - SP3 too heavy and the S3 already pushing the limits of "tablet", but I'm loving mine and wishing for more horsepower. A 1.37lb Surface Pro 4? mmmmmmm. I think MSFT will also want to showcase its partners at the event, so maybe we'll see those Dell Infinity Edge tablets or that secret HP tablet from earlier this year - I would bet heavily on a partner surprise(s).
The 950s, not sure what to think there - I desperately want to chuck my L830 (S808 and S810 + 3GB should solve the laggy-ness), but I'm not completely sold just yet. I'm hoping they wow us with something other than continuum. Regardless, I'll never ever see one in real life before I order so I'll have to rely on reviews....I really really hate that. Maybe we'll see some new hardware partners? That would be cool.
A per one of the previous posts, would not be surprised to see some new universal app announcements - developers don't "hate" windows, they're just waiting for the installed base - 100 million machines in the first few weeks should get their attention.
Should be a good day - someone please take my money! (Lumia, I'm looking at you...)