I really respect the OP for doing something that his kids will truly treasure. For a society today that has ZERO respect for history (both the advances AND McSteaks), that's a great thing.
The next 30 years are going to bring some major developments to service our human existance, with many of them not being so dramatically visible. At first, it will come from continual development of healthcare and technology advancements, with both ocean and space exploration once again becoming a focus as we continue to develop materials and (especially) ENERGY STORAGE capacities. At a cost scale (CHEAP) that makes many different aspects of our life more easily attainable and reliable than before.
Think about all of the internal combustion engines (generators, lawn mowers, vehicles, industrial applications) that could be replaced with electrical motors FEASIBLY, if only we had better electrical infrastructure as a society, or storage capacity for vehicles.
I'm certain my 2-year old will be sitting in a self-driving electric car by the time he greaduates college , and I would love to fly an electric plane that I didn't have to put fuel/oil into.