If you're just a road and trail guy, Serfas, Specialized and Canondale all make "inverse tread" tires that offer superb puncture resistance along with good riding qualities. They're not the lightest, but you'll have even less to worry about when it comes to road hazards.
As for going thinner: abso-frickin-lutely go with skinnies. It'll focus your weight on a smaller patch of road, increasing traction while reducing rolling resistance. For hard surfaces you want a small contact patch, for softer surfaces you want a large contact patch. One thing to keep in mind is your tire pump, since skinny tires are often higher pressure tires. My Specialized tires that I used on my old (unfortunately stolen) mountain bike were 85psi tires. The tires on my 700x23c road bike are 135psi. Just be sure your tire pump can safely reach the desired pressure.