Of the aged cachacas my favorite was the GRM, a 2 year old cachaca aged in two kinds of oak barrels. I loved the coconut juice flavor and oaky spiciness on the finish, like green peppercorns.
Then yesterday I picked up Esquire magazine only to read that David Wondrich rated it his favorite "sipping grade" cachaca as well. It's good to see that I'm not totally wrong all the time.
Anyway, look for it on the shelf of your favorite Brazilian bar or restaurant. In the store it costs about $60 so you'll want to try it before you pick up a bottle based on my not-always bad recommendations.