This is a good problem to have!! So often, everyone needs to cut and figure out how to save, how fun to be able to add something in!!
I think it really depends on your group and what's important to you...
The characters would be fun, and you'd get a lot of great pictures, and I suspect that whatever characters you'd choose, most of your guests will get a kick out them...
The uninvited guests sound like fun too...my concern would be that their comedy is much more interactive (I believe) and will depend, at least a little, on their interactions with your group...do you have people that will play along and have fun with it? If so, I bet it will be memorable and fun...but if your group is more shy or less likely to play along, it might end up awkward and uncomfortable...
Of course, that might be fun, too! Good luck with whatever you choose!
Brooke