With the range you all ready have I would have to say the best option for you would be the 24-70. I think with the 16-35 and the 17-40 you would be disapointed with the long end it just doesn't realy have enough reach to be that all purpose lens.

I have shot with all three lens the 24-70 is by far the most used out of my kit.

Good luck with your purchase.