We used to live in the area and always took I-49. I can't compare it because we never took another route, but it's nice and easy. We did start taking the loop at the southern end of I-49 to go to I-10. I can't remember the number, but it seems to save a few minutes off of taking 49 all the way to the intersection with 10.
We frequently pack our lunches and stop at rest areas to eat and run around. If you want to eat at a restaurant, you'll probably be going through Alexandria some time around lunch time if you leave in the morning (exactly what time obviously depends on what side of the Metroplex you live on), and it's a reasonable sized town with all the fast food joints with play areas you'd expect. You can probably look it up online to see if your favorite has a play area at any of the locations there.
If you want to stop at rest areas, there are plenty on the drive. We always pack some toys that make you move to get the kids going. When we don't, they don't take the opportunity to get moving. We especially like "guns" that shoot little foam disks and helicopters that launch disks into the air. They have to move all around to gather up the parts. Bubbles are good, too, if they'll run around and pop them.
