I agree with having a diet option, but don't have that as your ONLY option. I have reactions to anything containing aspartame (NutraSweet) and back when I was going through recruitment we had beverages for second parties and preference. Anyway, at one house, they served flavored sparkling water in cute cups- well the sparkling water was sweetened with aspartame and I was fine at that party, but it hit me halfway through the party at the NEXT house and I ended up puking in their formal bathroom. Needless to say I was cut by that house (But not the house that poisoned me)
Anyway, for food we had a bowl-mold that looked like a rose and we would make the rose chocolate bowls and then fill them with mousse. I think we got the mold from a cake decorating store. (we had a Mom make them, so I don't know how hard they would be to make as a chapter).