The sundaes are amazing, they look great and would be less of a hassle and mess. The cupcakes would only look good of they were iced extremely well which would take a lot of time. As a guest to your party I would much prefer the sundaes ( you are gonna have a birthday cake too I guess so there will be no shortage of cake). Plus sundaes would last longer ;D

Cupcakes! Girls love to decorate things, and if you are making your own sundaes the ice-cream might melt! Girls often times get distracted with conversation and you wouldn't want the activity to be spoiled by melted ice-cream! Also you could get different colored sprinkles and dye vanilla frosting fun colors so that they have a few options!

I suppose if those are the only two choices, I would go with the sundaes. I would prefer a chocolate spa and murder mystery though.

http://blog.ctnews.com/selden/2010/07/25/you-do-it-cupcake-bar/



For this- including the horoscope cupcakes.





OR





http://www.eatdrinkchic.com/post.cfm/diy-ice-cream-parlour-make-your-own-sundaes-buffet-concept-for-wedding-or-party