Or make it a blind tasting. Put the bottles in brown paper bags and see how smart everyone is. If you include variously priced wines, people can try to pick out the fancy stuff. Blind tastings are fun as long as everyone realizes that even experts are wrong more than they are right. Another approach is to taste the same wine or wines from two or more different vintages.
Tasters also see the changes that take place over time.
If you don't happen to have a string of vintages tucked away, a good wine merchant may be able to help out. Vintages don't have to be consecutive for the comparison to be interesting. No matter how you organize the tasting, one essential is to serve neutral-tasting food to cleanse the palate between wines. Bread, crackers, cheese and fruit are the standard fare. Water should be provided as a palate cleaner and also to rinse glasses between wines if necessary.