Tori,
of course it's appropriate to post pictures here! That's the whole idea -- to share what we do so we can all learn to do it better.

I don't know about the zoom you have. I've not personally used it. I have used the 17-55 F2.8 IS and it's exceptional. It's also expensive. I've used the 24-105 F4L IS and it is also exceptional and fairly expensive. I've owned and used the 17-40 F4L and it's a very nice lens at a very good price. I loved the image quality from it. I currently own the 28-135 F3.5-5.6 IS and it's very good and relatively inexpensive (around $300).

From my experience, the IS is a major advantage when shooting animal portraits hand-held which is the only way I do it. What can I say, I should probably use a tripod but I get better angles and quicker reaction time when I hand-hold.

To give you some comparisons, here's a shot with the 28-135 IS @ F5.6.



Here's a shot with the 85 F1.8 at F1.8.



And the 50 F1.4 at F9.0.



Here's the 24-105 F4L at F4.5.



And again at F8.0.



This is the 17-40 F4L at F5.6.



And finally (whew), the 17-55 F2.8IS at F5.6.



The thing to keep in mind is that all of these lenses produce excellent images when stopped down to F6.3 or smaller. The better ones produce equally good images wide open. You have to decide what type of shooting you do and then what lens will meet those needs. For example, most of my formal portraits -- either indoors or outside -- are shot with either studio strobes or a 580EX which allow me to shoot the 28-135 stopped down to F8. So I get some pretty decent sharpness out of it.

All of the other lenses I've mentioned here produce excellent images. It's more a question of what you can afford. The primes are wonderful but tend not to get as much use. There have been times when I couldn't get the shot without having either the 85 F1.8 or the 135 F2.0. But when it comes to controlled environments with controlled lighting, the zooms provide a lot of flexibility.

If you have a specific question, just ask. And please post some of your images so we can see what you usually shoot.

Jim