If you're looking for a really good century + with lots of climbing (12,000 ft or so), do I have a route for you! We did this on our own last year, and it was tough, but the sense of accomplishment was terrific.
The ride starts in Gorham, NH and climbs up over Pinkham Notch (past Mt. Washington). Down into N. Conway, out West Side Rd (and another right hand I can't think of the name of..) to the Kancamangus Pass. Take this up to Bear Notch road, and it's up and over your second notch. This will put you in Bartlett, NH, and from here you head UP 302 on a gradual 12 or 13 mile climb that ends in a VERY STEEP climb up Crawford Notch. This will bring you alongside the Mt. Washington Hotel. From here, continue on Rte 302 to Rte 3 and take that up to Rte 115. This is a very "rolly" section with some good elevation gain still. Take this to Rte 2, and climb your way back up into Gorham. Total mileage is somewhere around 108.
This took us about 7 hours with minimal stops. There are logical stops for food/beverage along the route, which helps. Let me know if you are interested, and I can send along more details on the actual loop!
BTW - we nicknamed this the Dirty Dozen ride

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SheFly