Others are right to say not to expect anything when you check in. Having said that, I've been upgraded to Club level or equivalent twice in 3 stays since I became Gold. But then most of them were on weekends, with lounge being closed. As Preferred Plus member, I was upgraded about 3 times in 10 stays to Club or equivalent (not counting "Preferred" rooms).

YMMV, but I probably wouldn't have as much luck if I was staying during the week.

BTW, I don't think everyone is Gold, but I'll agree that Gold isn't that special except for the bonus points.