I never understood the point of the vulture... someone enlighten me? They make decent scouts, but once you get wraiths... well, wraiths are better in every way.
Drop some mines, then the vulture can't drop anymore, and you get to watch as the mines either:
1) Chase after an enemy for a while, then lose track and burrow somewhere where no one would ever go.
2) Chase enemies right into your defending forces, then blow everyone up.
3) Blow each other up.
Then the vulture has the annoying pea-shooter, and it's as weak as paper...
I never had much luck with siege cannons either, outside of proxy base defense, or shelling down structures. They could shoot farther then they could see, so I'd always end up with lots of dead marines, lots of dead zerg, and my siege cannon blowing everything away indescriminantly. Plus, in 'tank' mode, the cannon lost ALL it's sex appeal. *PEWM*... *PEWM*... please...