I have 2 Saturns. I see them pretty often. Others above are right though... most haven't been sold for a while and they depreciate so quickly that they are quickly totaled or scrapped in the event anything goes wrong.
VUEs are so boring you don't notice them, but are very common. Even the 08-09 refreshed ones are fairly common. After they axed Saturn, they continued to produce them in '10 and '11 as the Chevy Captiva (fleet)
Michigan seems to have a ton of Grand Prix on the road still. Those and the often mentioned Grand Am.
Although Saturn ended with mostly boring products, sans the Sky, I liked the original product line when they started. Cars that could get you great mpg and bodies that wouldn't rust. I'm guessing they didn't clear enough profit with this formula which lead them to build product to the contrary.
Even though they mostly ran timing chains instead of belts, many of the early Saturns eventually developed major engine problems which were too expensive to fix or replace for many.
I see all of these cars every day. Saab being least common, but I still spot an average of at least 5 per week.
I don't know what happened to them. I've been busy driving my Plymouth.
I see Saturns and Pontiacs all the time, especially S-series since I owned one for 14 years. You see PLENTY of them in salvage yards, which is why I think they're still a great car to own- ready access to lots of parts. Their much-maligned 'engine problems' are most typically the fault of poor maintenance- unfortunately their engines take running with low oil less well than many, but properly maintained they'll run damn near forever.
The 'engine problems' are basically
1) they burn oil
2) nobody checks their oil
3) people don't change their oil
The engine is no more sensitive to running without oil than any others are.
There are still quite a few Pontiacs and Saturns in my area, mostly of the cockroach variety (1st. gen. Saturns, Vues, Gran Ams, Gran Prixs, G6s). There are some later Saturns still around; one of my coworkers drives an L200(?) for example. Sporting Pontiacs and Saturns on the other hand are rare. I barely ever encounter any G8s, GTOs, Skys, Fieros, or even Firebirds/Trans Ams, and most of the latter are rusty 2nd and 3rd gens.
Saabs are still fairly plentiful, but then again New England was always a bastion of the brand. However, the majority now are later GM-era or final models. It's very rare I will see a C900 or 9000 and GM900s/9-3s are starting to dwindle. Most of the survivor 900s and 9-3s are convertibles since they were likely garaged away from the road salt during winter. The 9000s held up better but are still afflicted with tin worm.
I see a decent number of Kappas around here- it helps that both SWMBO and I love the styling of them (though we differ on which we prefer- I like the Sky better and she the Solstice...) and make a point of noticing them...