I'm in for Arrowhead! I went about 8 years ago with my 2yr old daughter, but now she's a rabid 9yr old who begs me to use my spare season ticket on her every home week of the season. She's ecstatic to go to Arrowhead and compare crowd noise for the first away game she'll be old enough to remember. Already booked flights and I've been watching tickets.
Chiefs tickets already released at Ticketmaster, then pretty much sold out, and in the last couple of days a couple hundred seats are now available again. I just purchased section 343, row 4 for $97 ea. So, if you're planning on this game, it might be a good idea to snap up some tickets direct from the source ASAP before they're gone again. Otherwise, you're at the mercy of resale prices.
On a side note, my first visit to Arrowhead was awesome. Highly recommended. Even with a toddler in tow, dressed in Hawks gear, it was a welcoming crowd the last time. Plus, they aren't quite like the home crowd, but the Chiefs fans do pretty darn well with a high-energy and fun crowd. (I detest going to away games where the crowd can't so much as even clap for their team).