I have a 1984 Giant Schwinn. It's a World Sport. I covered the pink half of the Schwinn logos because no one remembers Don Johnson's version of Sonny Crockett or may not make the connection to the bike's age.
I used to be into the cheaper, chrome steel ones but when I started putting steady road miles on one or two I quickly realized the rear axle is not long-lived. I can keep a 120mm 5-spd alive with careful riding but not a 126. So it's worth finding a better one which is worth upgrading the rear hub.
If you're over 150lb, check out Nashbar.com. I got a 27" freehub rear wheel for $60. The rest of the bike is stock although it is a little slow shifting into the biggest or smallest chainrings.
Yeah, these things are great. I now like the "slightly better than department store" ones because you can easily find lots of them with few miles.
If anyone knows of an upgrade for the rear axle such as a 12mm rear axle for standard hubs, please let me know. It would be great to be able to use the stock rear wheel.