DirtRoadRunner

I'm in the market for my first "real" bike.

I live in St. Louis, which has many paved bike trails, and one end of the Katy Trail, a 200+ mile rail-to-trail with a packed gravel surface. I'm looking to use whatever bike I purchase as a new hobby, additional source of exercise (I'm an avid runner), and a way to explore more of the area I live in.

When it comes to aerobic activities, I'm more of an endurance junkie than an adrenaline junkie. I like to go fast, but I don't like hopping over rocks and stumps that much, so a mountain bike is immediately out of the picture. I was originally thinking of just buying a road bike (such as a Trek 1.2 or 1.5, but I'm open to other options), but they aren't exactly recommended on the gravel Katy Trail, and the city of St. Louis has broken pavement in some areas, and even the bike trails have many at-grade railroad crossings.

This leads me to consider a cyclocross bike (I'm not interested in the actual sport, at least at the moment, just a bike). I want something that I can use on the gravel Katy Trail, but will still be reasonably light and fast, and rideable for long distances (50+ miles) on pavement.

Will a cyclocross bike, like a Kona Jake the Snake (looks like a good option right now), work well for this? Or would people riding dedicated road bikes be wizzing by me on the pavement? How are cyclocross bikes for extended rides on gravel and asphalt?

My breakdown of riding will probably be 75% pavement and 25% gravel. I'd like to spend less than $1500 on a bike.

Thanks for any help!