Post school day decompression

I was cooking dinner at the time

While Lily is loving school, it is clearly kicking her nap-needing ass.  Once I get her into the car she is begging for quiet, which doesn't come easy with a three-year-old sister who is desperately happy to see her.  Once we get home she often runs to her room, climbing up to the top bunk and screaming in frustration when Anya tries to come talk to or visit with her.  Anya gets a dose of frustration as well, wanting to be with the sister she missed all day and yet repeatedly rejected while Lily searches for a way to come down from a full day of play and no nap.  Once Lily does get a little alone time, she does great and my girls start playing happily together until dinner time (with the regular squabbles and fights, of course). 

But I need to find a way for her to decompress, as she is clearly having a hard time finding it for herself.  One idea I had is to giver her a mp3 player and a set of earphones so she can tune out in the car while we drive home.  Another is to direct her up to Mark's office once we're home, a room accessed only by a ladder that Anya has yet to learn to climb.  The room is not (in any way) kid friendly as it tends to be a depository for all of Mark's crap, but she's pretty good at keeping her hands out of trouble.  Especially if we give her some things of her own to keep up there.  There's also the concept of forcing a nap on her at the late hour of 3:30pm, but I worry that this will lead us back into the land of difficult when it comes to bedtime.

I feel like I have somewhere to start, but need some more ideas here; so often, you people have the best ones.  Give, my dear friends who live inside my computer.  I could really use a brain storming session at the moment.