The best Saabs are those from before GM got their grubby mits on them - 'classic' 900s and 9000s. Totally robust and would go on for ever. I drove 2 to over 200K, and sold them running well. Gearboxes have been their only weakness. Their amazing engineering and build quality is why you still see so many around now.
Saabs decreased in quality the longer GM owned them. GM were basically asset strippers - they bought into Saab during the 90s, to compete with Ford buying Volvo and Jaguar - but whereas Volvos became better under Ford, Saabs became worse and worse under GM. GM wanted to plunder some of Saab's innovations and improve GM build quality, but in return they made Saab dip into their dodgy common parts bin. Thus you had engines which would blow up after 50K, and suspension which would need total replacement by 7oK - not to mention a host of electrical gremlins.
So newer Saabs are by no means as good and as long-lived as their forebears, and they will therefore cost you more to run. However, when everything works, they can still feel very good (and Saab kept some control on things like the driver ergonomics and the seat comfort.) I've currently got a 55 reg 9-3 TiD sportswagon, and I've had to replace most of the usual weak points identified by others, but at 167K it still drives well and handles beautifully, and I am determined to take it up to 200K at least (which at my rate of mileage will be by Christmas of this year!)
Matt - go for it - 9-3s are worth it if you can buy them cheaply enough, and I believe the later ones are better screwed together than the earlier ones. 9-5s are also lovely and cavernous in terms of interior space (loadsa bikes!) but less economical - and they are more dated.
However, the truth is, I still find most other cars boring to drive....I think only the Octavia VRS estate floats my boat (substitute appropriate Mr Toad metaphor) in terms of VFM loadcarrying rocket potential.