No offense, but this makes it sound like you don't normally get to high rounds,
But your quote have me an idea: you should have 4 special gaming lobbys each unlocked when you hit a certain round: lobby 1 : noob- survive round +1 lobby 2: zombie killer - survive to round +25 lobby 3: pro-survive to round +50 and my personal favorite, lobby 4: zombie analyst- get at least halfway through on any ee.
Now everyone can be sorted into little individual lobby's and you never have to worry about not finding anyone to do an Easter egg or being stuck with obnoxious children with their mics turned all the way up....
I normally go beyond round 40 on any map but nothing is worse than playing for 3 hours then 2 guys back out of the game. And for those that dont have hours to devote to beating their high score there should be some type of gratification for playing.