Personal opinion...a classic margarita is the best way to finish off a long days work.
A Classic Shaken Margarita
Recipe via ReadyMade
2 oz. 100% agave silver (blanco) - Recommended: El Tesoro, Sauza Hornitos, or El Milagro (which brings an amazing vanilla-ness to the party)
1 ounce Cointreau - you can use Gran Marnier if you happen to have some, but stear clear of Triple Sec
3/4 oz. fresh lime juice
1/4 - 1/2 oz. agave nectar (optional)
1. Begin by squeezing the lime juice with a juicer or citrus reamer. Use the spent lime half to rim a 4-5 oz. martini glass or a rocks glass, and dip into the salt. (If you like them less salty, only rim half of the glass.) Place in the freezer or fill with ice cubes and water to chill.
2. Pour the lime juice into a shaker, and add the orange liqueur and tequila, and the agave nectar (if that's what you're using). Fill the shaker with ice, and shake until your hands get cold, then shake some more. It's essential that it's very well mixed and diluted just so with the melted ice, and that comes from shaking. Don't skimp here; you're hard work will be rewarded.
3. Retrieve your glass, and fill with ice if using a rocks glass. Strain your shaken cocktail into the glass, and enjoy!