<p>Sounds like you've identified two focal lengths that fit your needs. I currently own a 50mm 1.4 and I used to own the 1.8 (the old one with the metal mount). I mistakenly thought that I would see a huge jump in quality with the 50mm 1.4; don't get me wrong, I really like the 1.4 but I didn't really see any noticeable difference in image quality. If I had to do it all over again, I would get the 1.8 and save the money.<br>
As for a wide angle, the 10-22mm is probably my favorite lens because I use it for landscapes so often.Stopped down it is extremely sharp.<br>
My most used focal lengths are 14mm and 22mm (roughly 35mm and 24mm on film). The 10-18mm appears to have image quality that is similar of better than the 10-22mm; I doubt you would notice a difference between the two. If it were me I would get the 10-22 because it offers 22mm while my next focal length is 35mm. Since you have an 18-135mm, you may not need the the 10-22mm, and a 10-18mm would probably be fine, unless you need wide apertures. If so, then a tokina 11-16mm might be what you are looking for, though it is more expensive.</p>