I recently upgraded to a touring-style road bike. Touring bikes have plenty of room for fenders and racks. The gearing is also a cross between mountain and road, so there is a wide range of gears. They also have wider tires than typical road bikes. The problem with touring bikes is that most bike shops do not keep them in stock. You might have to special order it or order through an internet retailer. jensonusa.com sells a Surly Long Haul Trucker for around $900. rei.com has the Novara Randonee for $950 or if you want really fat tires the Novara Safari for $850. bikesdirect.com has the Windsor Tourist for $600. You can also get a Fuji Touring for $950. The Bianchi Volpe is also a possibility at $1000. Some of those bikes come with racks, but you would need to install fenders.

I commuted for years on a hard tail mountain bike. I replaced the tires with specialized hemisphere EX tires. Off-road tires are not very good for commuting longs distances on pavement, but otherwise the mountain bike was OK. Mine was 15 years old and had no suspension and room for fenders. As others mentioned, fenders are a must. Racks are also good. Lights are a must at night. Bikes with skinny racing tires should be avoided.