First Long Cross-Country as a Pilot -- Any tips?

Thanks all.

Not planning an overly-long flight (2.5 hrs each way, likely,
depending on winds).

Done the DVD on a short trip prior (1 hr flight) with the kid. She
loved it. Then, about 15 minutes after her mom jammed 2 juice boxes
and 3 cookies down her throat, she puked. It was a calm day to fly,
so I'm hoping it was an over-stuffed stomach issue combined with too
much in-cabin focus on the DVD. Nevertheless, we were planning on
some sort of sleep-aid this time (I've heard benadryl...but saw
sudafed above), and have planned the flight for nap time. I.e.
skipping the DVD for now.

If the clouds allow, I'll plan for 6.5K-8.5K on the way up, 7.5K-9.5K
on the way down. Good tip.

Got the headset for the kiddie. Purple. She likes purple. I'll have
to figure out how to unplug the mic though. Kid also likes to
talk...a lot.

Great tips all. Thanks!