Standing seam is definitely the way to go, but it's expensive. The roof on my 28x48 house with a 7/12 pitch was $18,500. It's thick metal (can't remember the gauge but it's very tough), and was formed on site. I had it laid over 5/8" Advantec sheething with all the joints taped with Advantec tape.
While I adore my roof, it's built into my mortgage. Wouldn't have had any way to do it otherwise. Probably not an option for John.
They do make a corrugated steel roof that simulates the standing seam, it covers all the exposed screws. I forget what it's called, I almost went that route. but we built our house three years ago, I'm only 34 and plan to die there,. I didn't ever want to think about the roof again. We went with black metal. It's not as hot as my brother's asphalt roof, nor does it hold heat nearly as long. In fact, when you're up there on a sunny day, you can tell when clouds cover the sun because the temp changes in the attic quickly.
Last thing- make 100% SURE that they cover the Galvalume for 40 years. That's originally what I wanted, but the warranty on it was about half of what my black metal roof is. That pissed me off.