K.M.
Hi J.,
First off, I just wanted to say to you that you shouldn't bother with the people who are telling you not to use a stroller (when that is what works for your family) or those that say you should alter your lifestyle.
Even taking a child to the zoo, which is totally for the child, can be tiring for him. Why stay at home because your child doesn't want to walk. It doesn't mean he doesn't want to explore, right?
I have to take my 6 year old along with me to places where we will be doing a lot of walking. He weighs 49lbs and is 49 inches tall. He still fits nicely in the Maclaren Volo. He can read a book, play on the iPad, etc. if it's a long trek. The stroller is very lite, has an under basket and a carrying strap. You can even purchase 'extras' like a cup holder at Toys R Us.
I have also traveled a lot via airplanes with my children. I really liked having the strollers with me in the airports (you can gate check it right at the door to the airplane). Some airports are so big and very crowded. It's easier to maneuver with a child if he's in the stroller, not to mention being able to strap a bag or two to the stroller to take the weight off of you.
Enjoy your travels!