Oh I am an Architect. And I am going through the same thing you are doing on my own house. Right now it is all white–too blah for my tastes. I have a great home but I don’t like the color it currently is.
Wow, do those colors clash to me. Ouch.
For the OP, I like the slate, although I also like the sage green suggestions.
You’re thinking of copper. But that is pretty expensive.
Tin will rust, unless it’s galvanized. And galvanizing wears off eventually.
That first floor window makes your house look surprised. I love it.
Driving around town tonight and wishing I had remembered my camera, because there were some interesting paint and trim combinations. Most of them involved shutters though, and I’m not seeing shutters on your house.
But for all the houses, it wasn’t the main color of the house that made it interesting, it was the window trim. The best ones were those where the inside trim was white and the outside trim was a darker color – it really set things off.
One particularly cute house was a pale cream – almost apricot – with blue-gray and white window trim. It looked like grandma’s house, very cottage-y. Another was light gray with black and white window trim. Maybe the paint was new, because it looked very sharp.
Can’t wait to see what you come up with.
I like the three-color idea, but it’s hard enough just picking the main color.
Auntie Pam - Can you take some pictures? I’m going to wander around the historic areas of town this week to get some ideas.
StG
Ooooooo, shutters would be lovely. That’s what it needs.
Sure. 
It might be a couple days though – I don’t go to town very often.
Oh for heaven’s sake. All these years I though the B-52’s were making some sort of deep philosophical statement at the end of “Love Shack.”
I don’t know about paint colors at all, but that porch really needs a nice railing, with turned posts; it would set off the front of the house so nicely!
Edit: Oooooh, sage!
Update - I’ve bought yellow and grey samples. Look at the side-by-side pic and tell me what you think.
StG
The yellow looks dirty; the grey looks neutral. Did you give them an undercoat of white? Perhaps they look better in the sun or at a distance.
Of the two, definitely the yellow. But I think sage would be nice. We have a house on our street that is medium sage green with charcoal trim and it looks surprisingly pretty.
If you weren’t so far, I would totally come out and help paint. I love painting.
It was definitely overcast yesterday, which is good, actually. I need to know how they’ll look even when it’s raining or grey.
The yellow looks surprisingly bright in the sunshine. Almost too bright. And the grey doesn’t seem to contrast as much with the white trim as I thought it would. This is one coat of the paint over white. The trim is two coats of cheap white, and could probably use a third. A sage sample might be possible.
StG
Yellow houses are sad looking, something about the force fed cheerfulness in it lacks dignity in a house color. Paint your kitchen or bath yellow, the exterior needs more sophistication than pee colored paint.
It had to be said…sorry yellow lovers… 
creme yellow siding and hunter green trim.
or white trim like this photo. But creme and green are my favorites.
http://www.lelandsbarns.com/lelands/images/products/paintedcabinette/painted_cabinette.jpg
I agree too much yellow isn’t a good choice. You want a strong creme color.
Alright. The handyman came today and started pressure washing. A decision will need to be made soon. A new suggestion had now been made by three people that I should paint a deep barn red with white trim. Anybody want to voice an opinion?
StG
Already did, back in post #2.
Red is for barns.
Houses should be white, with green trim. I suppose if you want to be really radical, you could reverse that to a green house with white trim. But red is for barns. Period.
+1
I like that blue, but not the green shutters…