The Mt. Greylock Century in Western Massachusetts is 100 miles, 10,000 feet of climbing. I've done that twice.

The King's Tour of the Quabbin century in central Mass is 7500 feet of climbing in 100 miles... but 6,000 feet of the climbing comes in the last 70 miles (i.e., the first 30 miles are pretty easy). I do that one most every year.

I've done various supported cross-state rides that typically averaged 70, 75 feet of climbing per mile. Multiply that by 400 miles or so and you get some pretty big climbing totals.