Get kevlar-belted tires.
The ones most often used by folks here are
- Bontrager Hardcase
- Continental Ultra Gatorskin
- Schwalbe Marathon
- Specialized Armadillo
Each has its own fans and detractors, and its own pricing and availability.
I've used all of the above except the Schwalbe. I've found them equally puncture-resistant, although there are other differences between them. None are puncture-proof, but they're all worlds better than plain old stock tires.
Kenda tires came stock on my Giant too. They were flat city. I was never so happy as the day they both developed eggs (bulges) and my LBS told me to pick out any tire in the store to replace them. They had less than 1,000 miles.