Not an short, cheap, or exciting day of travel but I don't think you're going to find six segments on the Sunday before Christmas for less than $652. It looks like all the afternoon flights back into CHA are what's driving the fare up on most routes.
There's a long sit in CVG, but it shouldn't be too bad if you have club access.
Matrix didn't want to show that combined on a single ticket for that price (I'm pretty sure it didn't want to mix E and non-E fares on multi-city), but it's able to price it together for $701.80 all in Main if you want to avoid BE.
