Veronica runs slime on her road bike. I run Specialized Armadillo (Heavy tires) on my bike because I am slow, who cares about a little extra weight? I am even slower at changing a flat.

Make sure you are putting proper air in the tire. When my tires were worn (and there is no magical distance/time for a tire) I started flatting like crazy. Check your rims as everyone has said too. Good luck, flats are no fun!