Could there be a more valuable piece of clothing than the big hooded sweatshirt? Hmm, probably. But it's still a staple in any wardrobe. As I sit here sick, I'm extremely happy I have one. It's huge, soft, and warm. It's just comforting. But it's also versatile. You can throw one on over just about anything and stay warm in pretty cold temps. Go with the old standard of heather-gray and you can't get it dirty, and if you do you just about can't stain it. And it goes with anything. The big pocket can keep your hands warm all while holding the biggest of smartphones or iPods. The big hood can keep your head warm, too.
I took mine with me to Houghton, MI, last weekend, where the temps were in the teens. I didn't take gear for it, but we decided to rent snowmobiles one evening. Now, they will rent you helmets and a riding suit, but my big hooded sweatshirt was the only thing that would give me some neck protection. I got a helmet a little oversized and simply put my hood on and then put the helmet over it. Worked great.
Oh, and if you're worried you might split the rear of your pants somehow[*], wear your hoodie (an annoying, if not catchy nickname for the hooded sweatshirt). If you split your pants you can just remove your hoodie (yeah, you probably should have a t-shirt or something under it) and tie it around your waist. Hypothetically speaking, of course.
[*] This statement about splitting pants is in no way based on reality. It did not happen at a large public venue, it did not happen to me, and I do not own an extra hoodie because I had to buy one to cover the hole in my pants that I didn't have.