Is color a big decision maker? You're looking at two different colors, black and burgundy.
#1 is out, it's a 96 or older and not an SS.
#2 looks like a decent car. I've actually had good luck buying from a dealer too. There are a few reasons why, especially in today's market...
1) Dealers, and everyone, are hurting for money.
2) Seeing that it's at a Cadillac dealer, you can pretty much figure that whoever traded it in got stuck in the butt and basically gave it away. Dealers can fudge on used car prices a hell of a lot more than they let on.
3) Dealers have no emotional attachment to a car, like a private owner does. Private owners have a tendency of not wanting to budge a lot on price because they paid a bit more for the car just a couple years ago.
Also, because salesmen need to meet sales quotas each month, the best time to buy is the end of the month.
#3 looks pretty good too. Considering it's an 11 year old car, it could have been repainted just because of it being weathered. It also could have been in a crash, so you would want to go over that car with a fine tooth comb. Check ALL the mounting bolts on the doors, hood, fenders, hatch, and bumpers for tampering. Also look underneath the car for anything that looks like it may have been tweaked or messed with.
And if you're the least bit worried about the mechanics of the car, having it scoped out by a mechanic before you buy might be the best $75-100 you could spend, no matter who you're buying it from.