I stayed with the stock seat, but had it reworked and covered with leather by Rich's Custom Upolstery in Seattle. They have you onsite while the work is done so it can be fitted to the rider. Cost is about the same as the Corbin, but fits like a dream. I've done over 600 miles in a day more than once and could walk afterward. Seats make all the difference in the world when you're putting on the miles.
