Have the following lenses
100 macro (non-usm)
Though be gimped with my lenses as I really prefer shooting on my 10-22mm. So far this year, this lens accounts for over a 1/3 of all my pictures.
If you shoot ultrawide a lot, the 16-35/2.8 seems a natural choice - or the 17-40/4 if you want to save some $$$, carry less weight and don't depend on the best sharpness.
Did you really think the 24-70ii decision through? Maybe a lens with IS would suit tourism needs better, and after all you already got the 35mm & 50mm primes! Have a second look at the very good 24-105/4 kit (longer on the zoom end, w/o your 18-200 you'll have to tele capability at all) or at the Tamron 24-70vc which is available now if you want f2.8.
The decision for the 24-70mk2 was not specifically for tourism. I decided to pick it up because sometimes the 35L would either be too wide or too long in situations where i can't move where I am. I figured I'd get the 24-70mk2 as my midrange zoom and save the 35L for lowlight shots. With the 50 used for portraits.
I thought long and hard about the Tamron actually. I figured i'd be using the 24-70 in general to take pictures of people, and in that case the IS wouldn't be as useful. Also, i'm a brand whore/like having the best. I'll admit it. When possible I go canon.
I looked at my LR stats and telephoto shots only accounted for 1/6 of all my shots. And all those shots were of the moon, or planes flying overhead. I do plan on picking up a 70-200L 2.8 IS at some point, but will probably wait till next year when i have the money.