If I had to move away from Vegas, I'd come back just for Retro. Their Red Carpet (like red velvet) cupcakes and cake is the absolute best, and I have eaten them all over the country! The buttercream icing is heaven... you can taste the real butter, and they add just a hint of almond flavoring for added yummyness.
They also will make cakes for any occasion, and you don't need to call way ahead. The cakes are in the flavor of the cupcakes, so you can try the flavor ahead of time. All are absolutely gorgeous, but don't let the outside fool you.... it's the taste that gets me every time!