I'm in the same boat as you, I've got 2 older 10 speeds that don't get ridden as much as the 2 newer road bikes. I've been down the fixed path once before and that doesn't have any special appeal to me and I can't ride fixed from my house with our 1.5 mile steep hill. So I've made the older ones the foul weather gear with fenders, etc. Gets me out on days when I might otherwise pass.