Lifeforce. Would Lifeforce qualify? It's got vampirism after all.
Aside from looking great (something about being shot on 70mm film I think) I think it does have a touch of the logical/scientific approach to things that ReadyAndWilling is looking for.
If you want to slosh around in old Roger Corman produced stuff, then you have to see Galaxy of Terror. Joanie Cunningham from "Happy Days" gets squished, and some other babe gets raped by a space slug in an infamous scene. Bonus: Ray Walston's in it
It's great stuff, but I'm not sure there's any of the logical approach to things that ReadyAndWilling wants, it's pretty much tomb raiders being picked off one by one.