Going on vacation and need lens recommendation

I'd throw the EFS17-55 f/2.8 IS into the mix here. In my view it offers more than the 17-40 (which I own and use on FF and like a great deal) in almost every important way when it comes to a cropped sensor lens.

If you are convinced that you need the ultra wide angle range right away then your obvious choice is the 10-22.

What camera body do you use?

I use a 40D.

Dan, the IS lens is out of my budget. But it sure sounds nice.

"They are $10 dollars in difference (which is nothing) and have 7mm in focal length difference."

Those 7mm may not sound like much, but at the wide end 7mm makes a HUGE difference. At 10mm your field of view is almost twice as wide than at 17mm.

Based on your requirement for shooting indoors and in tight spaces I'd say the 10-22 is the answer, no doubt about it. It's very good optically, about as good as it gets.

The only "super wide" you mention; and your ONLY choice, if you must have Canon, is the EF-S 10-20mm.

17mm is only a moderate wide angle on your 40D.

If you want super wide and L glass, you need to buy a 5D or other "full-frame" body plus a 16mm- or 17mm- or so L lens.

It ,ay be price, but for architecture, noting beets the 24 TS-E. Lensrentals.com has a ggod price to rent one. It's certainly not my staple lens, but it gets the shots that no othere cans can.

http://www.lensrentals.com/rent/canon-ts-e-24mm-f3.5-l/for-canon

You said, "I WANT to get a super wide lens..."

24mm isn't wide at all on a 40D, although a tilt-shift lens can be great for architecture. And as JDM said, "17mm is only a moderate wide angle on your 40D." If you want a super wide Canon lens for a 40D it has to be a EF-S 10-22mm f/3.5-4.5. There are no other choices.

If you add in third party lenses there are more choices, but they all start at 12mm or less.

10-22 = 16-35 on the 40D, and 17-40 = 27-64. 27 is wide, 16 is ultra-wide. Right now the 10-22 seems like the pefect choice.