At MK the stroller station is on the right-hand side, just after you enter through the turnstyles. Depending on the time you get there and how busy they expect to be at MK, there are sometimes CMs set up in different areas near there who have strollers for rent. Make sure you have cash, though, (for the shortcut people)because they didn't take credit cards the last time we were there. Epcot's stroller area is on the left side of the park just before Spaceship Earth. I'm not sure about AK, but it's probably somewhere near the entrance. I think you made a wise decision about renting for your 6 year old. We have three DDs, 7,5 and 2, and we tried using a double umbrella stroller for the older two when they were about 5 and 3. It felt like we were pushing a ton of bricks through gravel all the time. We finally rented a double and breezed through the parks. What a difference!!!