Chicago Tasty Dogs is great. Love what they serve and how they serve it, and the quality of the food is good as well. While I do like the regular Chicago Style Hot Dogs, my absolute favorite is the Scala's Italian Sausage, especially with the hot giardinera on it.
Not too too crazy about the fries, but some people really like them.
They also have like gyros and stuff like that, but I haven't tried those. The decor is basically a bunch of pictures and memorabilia of Chicago style on the walls, and it's unobtrusive enough.
While I think it's worth it, keep in mind the prices are not hot dog stand prices. Look to pay around $5+ for one dog.