I've heard that MMF taste wonderful, but I am a vegetarian and do not eat marshmellows due to the gelatin. Does anyone have any tips on how to flavor the fondant to make it taste better?

I've used Wilton mixed with modeling chocolate. It actually tasted good. I mix it 50/50.

Well, what kind of fondant exactly are we talking about? Sating Ice and the rest come in either vanilla or chocolate flavors, both very yummy. If you make your own you still need to use gelatin. For flavoring your own you can use pretty much anything you like from koolaid to LorAnn oils, vanilla chocolate or any other kind of flavoring out there. Just make sure you mix your flavor in with the liquids before adding it to the powdered sugar. Your imagination is the limit.

I don't use MMF but I usually flavor my fondant with extracts. Just a few drops and you can flavor it vanilla, peppermint, or any other flavor