I tend to use Butter to grease the pan for European dishes but Vegetable oil for all other dishes especially oriental ones, would you use butter as an alternative to oil ?
Butter for French style dishes to be more creamy. Olive Oil for everything else. So, yeah, depends on the meal. You can add butter to olive oil so the butter won't burn, too.
Don't use vegetable oil unless you're deep frying, olive oil adds alot more taste and is a lot less gross.
i use butter for stuff like pancakes or anything sweet, and oil for everything else, i'm not particularly fussed about what kind. i try to put in as little as possible though with both butter and oil. i hate when things come out of the pan all gross and greasy.