I own the 16-35, which I really like, but have used 17-40 and also met a lot of people praising what the 17-40 can deliver.
If I was to do it again, I would have gone straight for the 17-40. In terms of sharpness the two are almost identical (you can even find posts from people that claim the 17-40 is sharper...).
I find the extra stop of 16-35 to be not so important in those focal lengths, for what I shoot. (Bokeh is usually not needed in wide angles and I handle low light on a tripod).
Now, 17-40 plus 50, yeah, go for it.
Since that's only my opinion based on what I personally shoot, just try to foresee how much you'll be using it at 2.8. If you believe that handheld in low light will be a considerable part of what you shoot, yeah, go for the 16-35.
Cheers,
G.
P.S. Something that is not mentioned: The 50 f1.4 is such a beeeaaauuuutiful piece of glass and value for money...