City, region, US, and world, plus any others you find interesting. Old and new maps, then and now, etc. I bought some 1800s era maps of India from a flea market for around $30 some time back...Obviously not everyone's cup of tea.
That reminds me, not exactly the same thing, but this book has some really nice then and now pictures http://www.amazon.com/Earth-Then-Now-Amazing-Changing/dp/1554077710/ref=sr_1_1?s=books&ie=UTF8&qid=1424323197&sr=1-1&keywords=earth+then+and+now
On a better vein, this coffee table book has some really amazing pictures and stories about India. I think you can get it for less than $5 now..Quite worth it http://www.amazon.com/gp/product/1587592177/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
I don't know what your position is right now..and the kids might be a little too young to understand and experience it...but travel! A week in Europe would be much more culturally enriching than a week in Florida...Not that there is anything wrong with Disneyworld. Bonus points for going to Asia, double bonus for South America, and triple bonus for Africa.