Personally I would suggest a simple Ribbed Mill Finish panel. Darker colors will fade over time in this Florida Sun no matter what they tell you and tend to look dirty after the birds start visiting. Mill Finish will also give you endless color options over the years for the house. (Mill Finish Looks like Raw Aluminum)

For Florida, I strongly recommend you prioritize comfort and sustainability, and select a "cool roof", i.e. one with a solar reflective index (SRI) of 0.30 or greater. This will save you money on AC (when and if you run it) and keep you much cooler when you don't. Cool metal roofs come in many great colors, e.g. Copper Brown from http://www.berridge.com/berridge_cool_roof_colors.htm

i'd do some chg for energy efficiency. for appearance, a simple light gray or raw aluminum look as cusano suggested. the house seems quite dark for florida.a light roof will look better and be neutral if you choose to paintt the siding in the future.
planting thick drifts of low maintenance native grasses would work wonders towards curb appeal.

Isn't Florida well known for its tin roofing? Have you considered that as an option? I seem to remember those were the traditional types of roofing and there was a reason (reflected sunlight ??- but I can't imagine how tin doesn't get hot?) -

I live in Florida and just did the same thing. You do get a tax break for using a cool roof (check with your roofing company about which colors apply) Do NOT use a green roof. You really won't like the color in 5 years and there is not much you can do about it. I would suggest a galvanized roof (silver) or what I used with is called stone (creamy/tan/grey)
In this sun those colors will hold and not fade away.