The in-laws are supposed to leave Monday morning, which means these are the last two days we get to spend with them. Mom in law is going to make taco casserole tonight, which I've never had, but I've been informed is rather good.
As for entertainment, I think we're going to drive them eastish, and go look at the San Jacinto Monument, where, in 1836 Texas won its independence. 1836 was also going to be the name of the Houston Soccer team, but they changed it when officials decided it would be offensive to the mexican population in Houston to name the team after the day their home country lost 1/3 of its land area. So now they're called the Houston Dynamo, after a character in Ah-nuld's "The Running Man." But I digress.
The plan also includes going to the Battleship Texas, which is moored right by the San Jacinto Monument. I've been a couple times, and always like touring old warcraft. The static displays at Lackland AFB, McChord AFB, and various other bases (There's a MiG-23 and a MiG-29 at Goodfellow AFB) are all really cool, and I have a shot of The Boy on the wing of a P-51.
Anyway, Dad in law should enjoy the ship, and Mom in law has expressed interest, as well, so hopefully it'll be a fun trip. The only other thing I can think of to do is drive down to NASA and let the kids have fun there - Space Center Houston really is geared more for kids than adults, I think.