The latest line-up of Aston models are not like the unreliable machines of yesteryear. I've had Astons from 1959, 1982 and 2006. The 1982, whilst rare, was massively unreliable!
The DB9 is a beautiful looking (and sounding) long distance GT. Very easy to drive and has the stunning Aston V12 under the hood. It's not really a 2+2 unless you're taking passengers who can remove their legs.
My own preference would be to go for the V8 Vantage which is equipped with the stiffest chassis this side of a Ford GT. The only downside is that you already have a 2 seater V8 and you would probably want something to contrast with the GT - making the DB9 an obvious choice.
So far, the DB9 has not shown any reliability problems - as suggested above, a second hand car would let someone else take the hit on depreciation -but make sure you get a warranty, big engine means big bills were something unpleasant lurking.
Very pretty car - what else can I tell you?! :biggrin