It's understandable turning down an invite to any old wine tasting--especially if you had a rough outing the night before. Though if you get the chance to taste several bottles from the same winery, but from different years, don't miss it.
Vertical tastings (though not to be confused with horizontal tastings, which aren't as kinky as they sound), as they're called, can comprise any number of consecutive years or even a random selection of vintages. The point is to taste the differences and similarities in several wines made by a single producer. This is what the pros do to assess the general characteristics of each vintage (as determined by the weather), the skills of the winemaker or even an estate's ability to make a wine with aging potential.
Wine professionals take vertical tastings very seriously. For you, though, it's really just a good excuse to throw a solid bash. If you'll pick up some wine knowledge and experience along the way, that's an added bonus.
It can be surprising to see the differences from year to year, and tasting the vintages side by side can be a great lesson in picking out individual aromas and flavors. Most importantly, though, you'll learn that older wines aren't always better.