Is there any cake fillings I shouldn't use if I am covering the cake with fondant? or does everything pretty much work?

Thks..just wondering

Good question! I'd like to know also!

There are varying thoughts on this. Some, myself included, have had problems refrigerating fondant (esp. MMF for me - and to a lesser degree Satin Ice). When it comes to room temp, it sweats and the MMF got soggy. For this reason, I tend to stay away from fillings w/ milk or cream that require refrigeration. That said, FondX is supposed to fare well under refrigeration/freezing, but i have yet to try it.

beachcakes...it makes alot of sense

thks for your reply

I haven't had luck refrigerating fondant cakes, either.
My rule is that any filling that can stay at room temperature for 48 hours should be fine. This includes fillings that use dairy, but have enough sugar to stabilize them. I've found resources for this on some other websites, but they aren't bookmarked right now. The Cake Bible has awesome recipes for fillings, and she gives the storage specs for every recipe, too.