Don't forget to check out cyclocross bikes., they usually have a disc brake option.

I don't regret disc brake option. Another option, if the bike will handle the increased forces, is to get something like a zipp 404 rim and have a LBS built it up for disc brakes. But 1. the fork must be able to handle the increased force, and 2. the frame must be solid enough. Since so many bikes are now sold on weight instead of durability. this combo is not always available in the bike you want.

Good luck.