Tokina 12-24 f4. Then get a 24-70 f2.8. Then get any 70-200 (or 70-210 f4)
That in my personal opinion, is the holy trinity for crop sensors.
(some would argue 11-16, 17-55, 70-200 is the way to go, but to each their own)
You could also just forego the 70-200 and the 24-70 and go for the 24-105 f4L IS on top of the Tokina (gives you a crazy 35mm eqiv. range of like 19-38/38-170 anyway, and will cost you maybe a grand or so for the two?) Then get a couple of primes for speed/DOF later.
Also, what are you using it for? If you're not shooting in dark places, you definitely don't need f1.8 on a zoom.
Have a nice day, Bluename.