A bit more info: when I was in college, I commuted to and from class on a Schwinn High Plains from around 1991, which at the time was still a very old bike. I couldn't have cared less about bicycles at the time, but I still remember how beautifully springy and compliant the ride was with the steel frame and big mountain bike tires. For the short distances I was traveling, it was perfect for navigating around obstacles, cutting across paths, bunnyhopping up curbs, etc. Since the trails around my house are of a similar distance and type, I think the comfort and agility of a vintage MTB may be the ticket. I also just discovered that we have a moderately technical single track trail right near my house, which makes me lean in favor of the mountain bike rather than the 700C-based hybrid.