Recipe for a good gin-tasting party:
1.) Print six, glass-sized circles on letter sized paper. Label each circle 1-6
2.) Place six glasses on the table. One on top of each circle.
3.) Pour a shallow glass (about 2-3 swallows) of each gin. I recommend in no particular order:
Gordon's
Hendrick's
Old Tom
Voyager (locally produced in Woodinville and AWESOME)
Plymouth
Dry Fly (Personally, I hate it. But others seem to like it.)
Bombay Sapphire
Tanqueray
The trick is to include both cheap and expensive, well-known and obscure brands. Keep your guests guessing.
4.) One-by-one, work your way through the gins, sipping water between each glass. Also, keep a handful of coffee beans handy to refresh your sense of smell as gin can be quite odiferous. For each glass, have your guests make notes about what they taste.
5.) When it's all done and everyone's picked their favorite -- you'd be surprised what tastes good when you don't know how much it costs -- start mixing cocktails!
When cocktail time arrives, I recommend having a few common mixers handy. Besides the traditional gin-and-tonic, I'd recommend:
Aviation
2 shots gin
½ shot lemon juice
⅓ shot Maraschino
⅙ shot Crème de Violette
(optional egg whites)
If that doesn't satisfy your tastes, try the Cocktail Database!
http://cocktaildb.com