Dan, here is a page that is interesting. I found some of the info about aging to be very general, but there are a few specifics in this article.

I have very little that is more than 2 years old; for me, "aged" is over a year. I know that the PD4s are great right out of a box that has a date of 12 months or less (dates stamped are package dates), and that if you wait too long, they'll turn "sick". However, they don't do it all at once. Light one at 20 months, and the flavor will change as you smoke it, some of of it having gone sick and some of it still being the wonderful flavor when they were 2 months out.

On domestics, some tobaccos are aged meticulously, in controlled processes, before they are ever made into cigars. Like Padron '26's. Can't really improve on these, I don't think. The only 26 I ever had that could've been aged was a 35 - it was punched and became tarry (probably because it was punched). I've smoked '26's up to a year after buying them - they are just as good if not better right out of the store.

I figure there are few specifics because opinions on flavor can be very subjective. I'm going to ask around - I've been curious too about which ones age best and which ones really don't benefit. I've always heard isom's for sure. Except for the PD4s.