Marvel Civil War did a good job of that. You could read the main book and understand what is going on, but the tie ins added a whole new level of depth to the entire series. Final Crisis did the opposite. The tie ins just cleared up some things that Morrison didnt have time to explain in Final Crisis. Either didnt have to explain or didnt want to. Im not sure.

There is a point where you have to explain things to people, because like Hilden said, you cant expect EVERY person who is reading Final Crisis to know every little thing in the DCU. It alienates the audience, especially the people who see the cover with Batman and Superman on it, and they just want to see a big event that has Batman and Superman fighting off some bad dude. Little do they know, that they will be lost within one page and then get turned off of big events right then and there.

I really should include a rant like this in my weekly reviews or at least give a bigger opinion on it.
Of course, i tend to think that it falls on deaf ears, but it gives the chance for other people to come in and address it themselves.