Saab as a company is nothing compared to what it once was. IMO GM have handled the marque exceptionally badly, and the current range shares a lot of major components with some godawful GM rubbish. Despite this fact, a hard-won image built up with rally wins, aero-technology and quirky, left-field styling and ergonomics lingers on. Once the intelligent alternative to Audi/BMW, this badge is now a sorry shadow of its former self. Don't buy one!
The A4 is like all Audis. Great build quality, cast-iron residuals and reliability, tasteful, inoffensive styling. The dynamics of all current Audis are poor. They just can't seem to build an involving chassis, or achieve a halfway reasonable ride (check this spoof story for an idea:
www.sniffpetrol.com). As part of the VW group, Audi shares many components with less prestigious marques. If you want the essential qualities of the A4, you can buy them much more reasonably from Skoda, Seat, and to a lesser extent VW themselves. I wouldn't go near an A4 - it's a waste of money.
I myself would buy a BMW 3 series, were I in your positiion. An independant, high quality company. BMW's just drive so much better than the competition. Rear wheel drive means the front wheels only have to steer, and thus stay uncorrupted by the transmission of power. Result - much more feel through the wheel, much more fun to be had whatever sort of driving you do.
The resale price will be excellent, all the more so because BMW are currently trying to ruin everything by going systematically through their range and hitting everything hard with a big Fugly stick. Chris Bangle has a lot to answer for. So buy a 3 now, before that gets ruined, and sell it when you're ready for lots of cash to someone who yearns for the days back in '03 when they made them look good as well as drive nicely.