Honestly, I think the NFL is just about the most "perfect" pro sports league there is. 32 teams, scheduling is a snap, the right number of teams make the playoffs, with a nice reward for the top 2 seeds that the other seeds don't get. Yet it's balanced enough so that quite often a 3-6 seed makes the SB. There's enough intrigue so that in the last few weeks there's usually quite a few teams in the playoff mix, but it's not a complete free-for-all, and almost always the teams that are in there are pretty good.
But IF they are hell-bent on making a change, I'd start with adding just one more playoff team per conference and still give the #1 seed a bye. It's still well worth playing for. So the WC weekend would be:
2 v. 7
3 v. 6
4 v. 5
Then re-seed after that, with the 1 seed playing the worst remaining seed, etc. I think that would be ok. But what you don't want is a hockey-style playoff format where so many teams get in that you routinely have an 8-8 (or worse) make the playoffs.