I think this JLA hardcover would be a great place to start diving into some classic DC stories. There are a couple of things to watch out for though: a few issues in, Superman becomes the “blue energy” superman from when his powers changed in the 90s. It was a stunt to draw extra attention to the character, and after like a year or two’s worth of comics he changed back to the regular superman. Also, Morrison really likes to reference old material — while you don’t need to have read any of the old stories to “get it,” know that guys like Professor Ivo, the Key, and half the other random characters you meet are being pulled from Justice League history.

There’s a few other random things, like the Green Arrow you meet is the son of the first green arrow, and Kyle Rayner is the Green Lantern (Kyle is actually my favorite Green Lantern, even more than Hal Jordan, but I’ll let you decide). etc. But like I said, I don’t think it would really matter too much, this is still meant to be a jumping on point. Let me know what you think!