Hi Again, Dave!
Sorry so long to get back. I have the D30, with the Sigma 15-30, Canon 28-135 IS, Canon 70-200L f4, Canon 50mm 1.8, and a "cheap" Quantaray 2x teleconverter. I feel like I am set with this- I promised my wife no more upgrades, but I don't feel like I need any more for a while (yeah, right!). I have heard good things about the Vivitar that has been spoken of- I have heard (and I tend to believe) that a lot of these 19-35's are made by the same company and rebranded under different labels, and that they are generally decent lenses. I came really close to buying the Tokina after I tried one out in a store. If money gets tight, I may sell my Sigma 15-30 and get a Tokina 19-35. I think the Vivitar 19-35 is the same lens as a Phoenix? and perhaps the same as some others with different names. Do I regret the D30? Not at all. I don't shoot much film, and for my needs I don't know if I ever will. The Sigma 17-35 never appealed to me too much because all the samples I saw were pretty soft, though I hear that it depends on if you get a "good one" or a "bad one".
Just a word of warning about the Sigma 15-30... If you do get it, I hear that it is best kept on a digital SLR, as it tends to get soft really quick at the edges when you use it full frame, such as with film. But that is a general rule when you get really wide with any lens. My brother shoots the Canon 16-35L with his EOS 5, and it gets pretty soft on the edges.
Also, if you get the Sigma 15-30, you have to switch to manual focus and back to auto with a switch AND pulling a ring back and forth. Just something to keep in mind for any owners of this lens as I about broke mine on the first day not doing this!
It is an awesome lens, though. Highly recommended if you can justify the cost. It is about as wide as you can go on a D30 for a decent price. Plus a somewhat hidden bonus is the close focus capabilities of the lens- you can get up to 11.5 inches to your subject, which is pretty good for that "in your face" type of shot!