Hi BHS65,
Given your age no matter what asphalt shingle roof you choose to go with it may NOT be the last roof you will ever buy. In 25-30 years or so you will need a new roof.
I understand your concern on the look of the metal roof. I talk to people on a regular basis that share that same opinion. Take a look at a product called DECRA. It is a stone coated metal roof system. Therefore you get the benefits of metal without the metal look. Also in some cases it can be installed over your existing roof without the expense of tearing off the old roof. As true with anything, DECRA is only as good as who installs it. So keep in mind just because the synthetic slates, and metal material will last 50 years it has to be installed in a manner in which the labor and other roofing accessories will last 50 years.
As for price on the low end the cost is 2 1/2 times more. The high end is 4-5 times more. IMHO In 10-20 years asphalt shingles will have little to no market share in the roofing industry.