Stuff that I MUST HAVE:
Air Conditioning (I HATE HEAT!!!)
Cruise Control (bad hip; gets real difficult to push the throttle down for hours on end)
Diesel

(see sig)
Single-disc CD player (to assist in keeping me awake on long trips)
Cloth seats (I hate vinyl/leather; the 300D is the sole exception to this, although I want to either replace the seats or get seat covers)
Stuff that I like, but don't absolutely need:
Power windows (beats leaning over to roll down the passenger's window from the driver's side)
Sunroof (never thought I'd care for it, until I got the 300D)
Heater (nice for cold nights, but I'd rather have workinc a/c than a working heater)
ACC (it honestly comes in handy, although I'm sure I'd be singing a different tune if mine were to break {knock on wood})
Adjustable seats (power preferred, although manual works as well)
Tilt steering wheel
Center console
Stuff that I don't care for:
Automatic transmission as standard equipment (my back's happy that my car's an auto, but I wish it had been available with a manual)
Most of the brand-new electronic systems (phone, navigation equipment, etc - I don't know what all they have these days)
Electronic-controlled engines (I know there's no choice these days in a new vehicle, but I like being able to do my own work)
Leather or vinyl seats (I find them very uncomfortable)
Gas engine (same reason that I like diesels)
"Sealed-For-Life"/maintenance-free anything (seems like an expensive repair down the road to me)
I'm sure that I can add to the list