I have the Sunpak Super 383 Auto. It is pretty much on par with the Vivitar 285HV (and costs about the same amount of money), with the primary difference being that the Sunpak unit can swivel but has no built-in zoom head, whereas the Vivitar unit has zoom but no swivel. Both have the same guide number, 120 feet (~36 metres) @ ISO 100. I personally think the controls on the Sunpak are a lot more user-friendly than the Vivitar one, but that's a pretty minor issue. In general, if you're looking for a good all-purpose generic auto flashgun, you can't go wrong with either one.
For different shootings. My Vivitar has 3 zoom position; wide, normal, tele.
Fotoguide, and a few other shops at PP are selling that. In fact, Alex Photo at the 2nd floor is selling a 2nd hand Vivitar, saw it yesterday. Darn, and the color of the calculator looks better then mine.