Depends on what you shoot and what style you like. For most of my photos the longest lens I use is my 50/1.4. I love it. I get delicious results almost every time. Other than that I use the 10-20 - I just wish it went below f/4. I have a love/hate relationship with that lens. Next on my list is a 24-70/2.8 b/c I'm tired of swapping out lenses so much, particularly at car shows. For car shows, landscapes/cityscapes, and most of my night photography I use the 10-20. for picking out details in a setting and some portrait stuff I use the 50/1.4 or the 28/1.8.
And, yes, I love the steel wool. Really lights up the night.
Just be careful you don't set your surroundings on fire. Happened to a friend of mine.