Go with the slanted roof on top of the coop and run. I used pressure treated 2 x 4's for the corner posts and bottom boards of my run with regular builder's grade 2 x 4's for the remaining posts and bracing. I covered the original run with corrugated steel roofing. I built a 4 x 8 extension and used one corrugated steel roof panel and one of the heavy duty UV filtering panels on that to allow more sunlight into the run over the winter. We didn't get much snow last year to worry about shoveling, but I'm sure this coming winter will be more snowy. I like to keep the inside of the coop as dry as possible. Fishers are seemingly everywhere in Massachusetts but I've heard about coyote sightings closer to the Boston area and just a few weeks ago foxes and bobcats munched their way through a few free range flocks in the next town over from me near the New Hampshire border. I have a flat roof on top of my nest boxes and the girls like to sit in front of the window and watch the neighbor's yard at times. It also is helpful during the occasional spats when the hens want more space then they really need. It's the first thing I scrape in the morning, not really a big chore. I used heavy duty clear shower curtains last year to wrap my coop. They worked really well especially with the grommets in them make hanging them much easier. Good luck with your flock.
