Yesterday I rode the entire Avenue of the Giants (60 miles total) with a rider who is much stronger than I am. The wife came along for the first 15 miles. It was a very tough ride for me, trying to keep up. He dropped me on all the hills toward the end, but I didn't embarrass myself too badly.
I almost bonked after one hill 20 miles in to the ride, but was surprised to find some reserves later on. It felt good to really push myself that hard.