We were there for about 4.5 hours on a Thursday. It wasn't busy on that day. We could have used another 1.5 to 2 hours to see everything and that's not including the extended tours.My parents drove 200mi each way from southern Florida to visit the Kennedy Space Center last week. They were there from 9am-6:30pm and said they weren't able to see everything. Lots of standing in lines, but I think they liked it and wished they had more time there.