I want to shoot wide-angle landscapes, buildings and cityscapes, largely early mornings and before/after sunsets + some street scenes and people.
Disclaimer: I shoot a lot of travel & landscapes on a Canon 40D. Their 24-105L is my "main" lens. Canon's reputation for not-so-great wide angles led me to look elsewhere several years ago before they got their act together.
I bought the Tokina 12-24 f/4 when it came out. When Tokina released the 11-16 f/2.8 version, I upgraded. Note that in Canon mount both these lenses use a built-in micromotor, but in Nikon mount I'm not sure if they made a screwdriver version of the 11-16 but I'm pretty certain that the 12-24 is available with both AF styles (the screwdriver version certainly being cheaper & perhaps available used).
Though the extra length of the 12-24 was nice as it gave something approaching "normal" focal length, the extra f-stop & resolving power at wider apertures of the 11-16 have been well worth the trade-off, & the extra mm on the wide side makes it a little more fun. I do miss the ability to use the 24mm end as a more-or-less "normal" length though; the 11-16 really is a dedicated ultrawide whereas the 12-24 is more versatile. Optically the 12-24 is quite nice once you stop it down to at least f/5.6, but the 11-16 really starts to shine around f/3.2-f/3.5 and suffers less from low-contrast flare when close to wide open.
You don't mention what lenses you already have for your D90, but for me the following is clear:
- If you've got an APS-C "standard" zoom like Nikon's 16-85 VR, then you'll probably be most satisfied with the fast aperture & wider coverage of the 11-16 f/2.8.
- If you've got a full-frame "standard" zoom like the 24-120 VR then you may be happier with the extended versatility of the 12-24 f/4 that better complements your main lens, unless you prioritize low-light ability over practicality.
...that's my 0.02...