Being a bit of a devil's advocate here..................
If you need good low-light performance, and you want to do some video work (and video is great for trips), then you have to go for a 70D.
There are just so many advantages to the 70D, that you will be amazed by it's high ISO performance as well as the new processor it uses.
The screen is like night and day compared to your 40D and the FPS of the 70D is also very good, to say nothing of the excellent focussing system it inherited from the 7D.

The Tokina 11-16 is a great UWA lens, and if you need to save $$$$, then buy a used one for a good saving.