One fun thing to do when you're buying airplane tickets online is to forget to reserve seats. Then, when you arrive at the airport, you will be assigned whatever seats are left, thus ensuring that you and your three-year-old are separated by fifteen rows, and your 6'5" husband is crammed into a window seat and spends the entire trip sending laser beams of hatred burning through the back of your skull. What fun! What a fun way to start your trip!
Fortunately, some friendly seat switching put Jackson and I next to each other, our rental car was luxurious and full of gas, and once we arrived at the Hyatt and realized that we had been blessed with the most insanely comfortable bed known to mankind the trip began to resolve itself rather pleasantly. The next day Jack had to look at some antique doors for a house he's building, so the three of us got to roam around Eron Johnson's Antiques for an hour looking at Chinese lacquer cabinets, model pirate ships, and the mahogany interior remains of a dismantled Indian palace.
My family was remarkably low-maintenance; we spent an entire rainy Saturday afternoon playing gin at the house of my brother with the two children and three dachshunds. We also spent a relaxed Sunday morning looking at dinosaur skeletons at the Museum of Nature & Science. The only other kid-friendly thing I could think of was to go to the Denver Zoo. The last time I was there, probably in the early '80s, it was one of those "I will never again spend my afternoon looking at a psychotically depressed gorilla" days; what really capped it was a rare white tiger pacing back and forth behind glass in a tiled cage -- like de Sade at Charenton without the defiled altar boys. Twenty years later, though, and they've done a lot to make the trapped animals appear to be more comfortable. Also, a lot of the exhibits had glass in front of them, like a pet shop, so we weren't clobbered by a lot of sun-ripened gorilla poop. Though I suppose the gorillas were.
One thing I recommend doing before you take your next vacation is to order a bunch on stuff online and make sure it's delivered while you're gone, so that when you get back the usual mountain of bills is stacked on top of a bag of t-shirts from toothpaste for dinner, a used DVD of West Side Story, and a ten-pound book and two CDs of every cartoon ever published by the New Yorker.