I've played FF7 once the whole way through. i tried going back and replaying it but I can't get past the 1st CD anymore.
I own Advent Children. It's alright. I think they focused too much on trying to make awesome fightscenes that they just didn't care about the story. I had to watch that thing like six times to fully understand what's going on. The script is just so... blah... that its just hard to follow. Short and uninteresting plot points followed by very long and drawn out fight scenes. The only think really worth watching it for is the fancy CGI and the final fight. And, of course, to see all your favorite FF7 characters.
The story really killed it though. I would have rathered it be actually be the story from the game. Would have game them time to fill in some plot holes.
Didn't play any other FF7 releated games. Almost picked up Dirge of Cerberus and Crisis Core once but didn't. lol