Another thing might be to use some of these, one or two per flavor:
https://www.fasttech.com/p/1640900
Since these have removable drip-tips, you could do a couple per flavor, and have people just keep their drip-tip.
(Sorry to re-post, but I DO really love this concept).
Other Ideas:
Have a Vapetender, to serve e-liquid, and provide guests with whatever equipment, liquids, etc. that they need.
Have a contest where your vaping guests bring their favorite e-liquids, and folks vote on the best one.
The "guess the vape" idea from iamthevoice is a great one! Like the "Hell's Kitchen" "name that food" challenge. But you will need to use a head like the above, where each person has their own drip-tip. Get some simple, but strange ones (I am thinking "black tea", "Litchi", stuff like that.)