Hi, this is my first question posted, I'm pretty new=) I have only used a basic buttercream (the one in the whiltons books) under the few fondant cakes that I have made. I was wondering what other options work best under fondant. I am in AZ so it can be warm so I would need to know if that is something I have to worry about when using certain frostings. I like the basic buttercream but would like to play around with other types. Maybe some that are not quite so sweet or just are different. Kind of a broad question but you guys are the best in the bus!

I use Indydebi's buttercream, which stands up better to heat than the Wilton recipe It also doesn't have that greasy feel to it that some frostings do.
http://cakecentral.com/recipes/6992/indydebis-crisco-based-buttercream-icing

I only ever use home made Almond paste, it's like marzapan.

I generally use one form or another of BC (not Wilton's), however, I recently tried Planet Cake's ganache recipe (not whipped) under fondant/modeling chocolate covered cakes....worked fabulously! Apparently many of the cake artists in Australia use this method. It went on like a dream and it was great for getting the corners of the cakes extra sharp. I definitely plan on using it again.

Chocolate ganache, definitely chocolate ganache. And it's awesome in the heat (esp dark choc ganache)

Do a search in forums for the thread "never using buttercream under fondant again"
There's LOADS of info there about using ganache

Thank you all for the help. I am gonna go find a great ganache recipe to try!

The best one for covering a cake is a ratio rather than a recipe.
2 parts dark choc (not compound choc) to 1 part pure cream (not thickened with gelatin)

So, for example, if you have 500g of choc you'd use 250g of cream.

Break the choc up. Heat the cream until it's just boiling, then pour it over the choc. Let it sit for 2-4 minutes then use a hand whisk and whisk it until it's smoooth. Leave it uncovered until it's cooled, then cover and let it sit overnight unrefrigerated. It's good to use when it's the consistency of peanut butter. Use the fridge or microwave (carefully!) to get it to the right consistency if necessary.

Have fun!