Yeah, a lot of the "grandparent" age people are like 4 foot nothing
, but as I walk through crowds of businessmen during my morning commute I'd say the average guy is AT LEAST my height (5'8"-5'9"), and a lot guys who are taller than that.
As JohnBraden said, you'll probably be able to see over most people but you're not going to be some kind of giant.