First, did I do this right? When you post in two forums you put "XP" on  it, right? It's about food and about favors. So, I'm putting it in both.  Let me know if I did this wrong!
I have always thought candy  bars were a really cute and fun idea, but I am one of those people who  thinks having candy and cake is excessive. Especially in a situation  like mine: I am having a cake large enough to serve everyone two pieces  and still have left overs.
I have this cute idea, though. I could  set up the candy bar, and have goody bags on the table to turn it into a  "Mix-n-Match Your Own Favors" candy buffet. That way I can have the  cuteness,the fun, the color theme matching addition, it takes care of  party favors, and it doesn't feel like excess (because it's meant to be  eaten later, not right there. Of course, guests are welcome to snack on  it day-of, too.)
However, I wasn't sure how much I liked this  idea. My fiance pointed out that if someone wasn't watching their kids  they could engorge themselves on candy and wind up getting sick at the  party. This is a good point, but we're only having two for sure kids,  and two possibles. Another thing I took into consideration is that the  two for sures are coming with their single father (no date,) so, he  won't have any distractions.
Another thing, would adults like  this? Personal like/dislike? Candy is enjoyable for kids but not always  adults. The few times I see candy as favors are when they're  personalized. So, I was thinking of maybe getting one type of candy  personalized to place at the center of the buffet.
Any other pros/cons I didn't think of would be much appreciated!                
                             
        
Re: XP: Cake + Candy Bar (kinda long)
I had a candy bar at my wedding(which was an adults only wedding) and it was a huge hit.

Good Luck!
@chickenbut
I would love to send my guests home with cake but most of them will drive 8 or more hours that night to get home, presumably.
My friend said she'd take home ALL the left over candy, haha. Guess that solves that problem! : P
My Planning Bio - Update 8/5/12