Definately studs at work or school or anywhere you are trying to look professional. Classy dangle for dates and playful hoops for girls night out. I really like the Chanel diamond studs when the hair is pulled back in just a pony.
Me don't really car but big, dangly or big hoop earings are a bit much...
I have a spiral that loops through 3 holes in each of my ears, plus an additional 3 studs in each ear. Having so many piercings kind of limits my jewelry options (funnily enough). When I had fewer, I liked wearing dangly earrings but now I like the simpler look of studs. Dangly earrings would make my ears look way too crowded.
I prefer the dangle earrings for more formal wear and occasions. Studs are good if you do a lot of physical work because you don't have to worry about safety concerns and such. I wear studs a lot for that reason, but if I could I'd wear dangle. They just look nicer.