Colleen at Cocktails.About.Com notes the interplanetary twine of Kentucky Derby Day falling on Cinco de Mayo, which could confuse some topers, but hopefully the experienced will rise to the challenge.
Colleen writes of the Derby's staple, the Julep:
Anything but Southern Comfort, in short, which is, alas, is often what they serve at the Derby itself, although this year Early Times and Woodford Reserve also have deals with the Downs. That all reminds me of a beautiful post on the subject of Derby Day Drinks at Martini Republic from a few years back; way more informative, and destined to be referenced through the ages.
It's common knowledge that the Mint Julep is the drink of choice for watching the Kentucky Derby. The question at hand, however, is which bottle of bourbon to use. As you can see by this list on straightbourbon.com there's a lot of bottlings to choose from, which you choose to use is a matter of personal choice. Maker's Mark, Woodford Reserve, Knob Creek and Jim Beam Black Label are a few of my personal favorites for this minty drink. However, there's no need to stick with the original recipe, you can add a little extra flavor by using other spirits in conjunction with or in place of the bourbon. Go fruity with a Pomegranate-Mint Julep by using equal parts of PAMA Pomegranate Liqueur and bourbon or a Georgia Mint Julep with equal parts of peach brandy and bourbon.
(BTW, did you see that my horse Street Sense drew post position seven yesterday?)
Of Cinco de Mayo, she says:
No matter which tequila cocktails you decide to shake up for your fiesta, do yourself a favor and pass up the cheaper bottles and go with a top shelf tequila. Don Eduardo, Voodoo Tiki and Sauza Tres Generaciones have great blancos with a light agave bouquet that is perfect for your fruitier mixed drinks and gentler tequila shots. Check out the reposado tequilas of Corazon, Cabo Wabo and Casa Noble for a Tequini, Envy or other neat cocktails. Of course, if you're the straight sipping type you'll want to look for the anejos, of which I highly recommend Tezon, Patron and (the ever satisfying) Don Julio.Here she got a little more endorsement-y; I gotta think the utterly smooth Corralejo, the rare tequila from Guanajuato, should make the list of premiums.
There's also a fight that day, I hear. You can safely drink Bud for that.