I do a lot of UI design and because of this, I normally have to use pretty neutral fonts like Helvetica and Droid. In order to add a bit of flair, I'll use different weights and mix things up between ALL CAPS and normal case.
Sometimes I find myself guessing if it's best to use a thicker weight vs. caps. Does anybody have any tips or general guidelines when it's best to use one or the other?
I remember reading before that the bigger the font, the thinner it should be so there's a common thickness between different sizes within your font scale. But then does that not make everything look too generic as not enough contrast is given?