I need a lens for city photographs. Nikon mount?

I'm going to New York and wish to take the typical city pictures. I also need a new lens that helps create sharp pictures. I have a Nikon D300 and currently use a Tamron 70-200mm f/ 2.8 and a Nikon 50mm f/ 1.8. I fancy a wide angle zoom but I have no idea what to go for. It needs to be affordable but I don't really fancy going over f/2.8. I want a fast lens.
When I say affordable, I mean that I don't want to spend like £800 on a lens that Tamron sell for £200. I've had a look at the Tamron 17-50mm f/ 2.8 but there are mixed reviews on it.

THE best lens for what you want is the Tokina 11-16mm f2.8 lens. Reviewed as one of the sharpest lenses out there - even outperforms the branded equivalents.

It may be a bit too wide, as it does mean you'll have nothing in the 16mm to 70mm range, unless you can afford that and the 17-50mm.

Well, you'll never get a ultra wide angle lens faster than f/2.8, with the Tokina 11-16 being the best.

Personally I would think the 8-16mm range doesn't need to be as fast as f/2.8, so I would suggest you go for something inexpensive such as the Sigma 10-20mm f4-5.6, it's not the best ultra wide angle, but you don't need the wide open performance, in this range. Add to that a AF-S DX Nikkor 35mm f1.8G, it's not expensive, and should add up to around about the price of a 2.8 UWZ.