Well for months I debated between putting on a metal roof or using shingles. Metal costs a tiny bit more but is many times faster to install. Well the folks at 84 lumber had Architectural shingles on sale for $86 per 100 square feet. That compares to about $105 everywhere else.
First I had to remove the flat roof over the deck and replace the last 1 to 2 feet as they had rotted out. Then I put on a new roof using roll roofing. Basically you nail down a 9 to 10 inch wide strip around the outside edges. Then cover those strips with roof cement and then put the new roofing on using that cement, and nail down the top edge. That way no nails are visible when it is done. However it leaked the first time it rained because the cement was not dry yet in the seams.
Here are some "Before" pictures, first one of the main roof then one of the carport roof.