Canon ? Full frame or ultra wide lens for 1.6 crop?

I've had a 40D now for a few years and have tried to get out with it as much as I can. I would say that my passion for it has only increased as my shots have improved. I now mostly enjoy travel photography but shoot a lot of family portraits some landscape and sports as well.

On a recent trip I borrowed a friend's 5D and really loved using my 17-40 for ultra wide angle stuff.

Now that I returned his camera I find myself scratching my head and considering getting a Tonika 11-16 or should I just stick with lenses that are will work on both crop and full frame and instead use the $700 bucks on a used 5D???

Thanks for any insight...

the tokina 11-16 is pretty bad ass.

Thanks Joe, your tip actually was the initial thing that had me look at this lens, but then I realized I could pick up a used 5D and use my 17-40 and get about the same results... and at the same time have a second body.

Make sense? I don't want to buy a bunch of crop only lens as I think I might eventually switch to a full frame.

I like my 70-300 lens for my cannon to get that close up picture, but one of my favorite pictures of the season was a wide angel lens. i think it all comes down to your personal preference and possible what you will be using the pictures for. i don't know if that helped at all.

yeah tokina 11-16 2.8... been looking forward to get that one... going to order really soon