good recipes in here. i have a few tips that may or may not be offensive to some:
a) only use key limes. any other lime will be too harsh. keys are the only way.
b) for your lime portion of the drink, use half roses sweetened lime juice, and 1/2 fresh.
c) I like to tear up a few fresh mint leaves and toss them into the shaker before shaking the drink.
d) shake like hell, then shake it some more.
e) always finish off the drink with a squeeze on a fresh, small wedge and toss it in after it's squeezed. you might need to reduce the lime juice component in the shaker to balance it out; i just prefer the fresh lime floating around on top.
Tequila preference is very personal. I tend to like 1800 reposado for a base tequila. True to the original recipe, I also like to mix my tequila portion as about 1/3 of the drink by volume, with that portion comprised with 2 shots reposado, and 1 shot silver.
For tequila sipping I really like Milagro's single barrel reserve. There are better single barrel tequilas but it's easy to find.
My latest sipper isn't tequila, but it's close cousin, mezcal. I was introduced to mezcal while in NYC, at a fabulous tequila bar named Mayahuel. Co-owner Phil Ward is one of the best bartenders in the country and I had a chance to sit down with him pre-opening to try on several different cocktails and mezcal sippers. If you're in town it's worth a visit - on 6th in East Village, where all the best bars are located.
You can find some of Phil's thoughts on mezcal here:
http://dinersjournal.blogs.nytimes.com/2009/04/23/getting-comfortable-with-mezcal/
If you're adventurous, look up a few mezcal recipes for cocktails. a margarita it isn't, but the smoky flavor of mezcal can make for a very pleasing drink.
cheers,
-ike,