Most of what I'd normally suggest at that price point (Boxster, M3, 'Vette, etc) would probably ride a little harsh if you're looking for luxury.
A good choice at the low end might be an Audi A4 Cabrio. Nice interior, good looks (IMO), and not too harsh. If you're looking for something smaller, a loaded TT Roadster might work, it's more of a GT than many competitors.
Overall, though, I'd probably go with a CLK in that price range for a "luxury" convertible. A slightly used Jaguar XK8 might also fit the bill.