This is my new Favorite Cocktail, for my introduction to which I copiously thank Nicholas Jarrett[1], Apothecary[2], and Plymouth Gin[3]. It's a wonderful middle point between the Aviation and the traditional Martini (the one that's closer to the Martinez, not the "dry" version that now horrifies me).

2½ oz Plymouth-style gin (the easiest obtainable version in the US is Plymouth-brand Gin, see also [3])
½ oz Crème de Violette
½ oz dry vermouth (I recommend Noilly Prat or Dolin; substitute LIllet Blonde for a sweeter, softer taste)
2 dashes orange bitters (although I don't think much of it generally, I actually like Fee's for this. I think Angostura's and the Bitter Truth's may also work well but, regrettably, I don't have any of either at the moment to try. Regan's is too assertive for this.)
½ barspoon (about one sixteenth of an oz) absinthe
Optionally: 2 drops (use an eye-dropper, really) vanilla extract (I recommend Penzeys[4])

Stir all ingredients well (30 seconds or longer) on ice, strain into a cocktail glass, garnish with a lemon twist.

Should you have the bar equipment available[5], don't mix the absinthe in, but mist it over the top. That tip's shamelessly lifted from Nick and [2]'s new bartender, Preston.

[1] Formerly of [2], now of the Franklin Mortgage & Investment Company -- http://www.thefranklinbar.com/
[2] http://www.apothecarylounge.com/
[3] http://www.plymouthgin.com/
[4] http://www.penzeys.com/
[5] http://www.amazon.com/gp/product/B00004SPZV