What tyres are you running? I have great experience with Continental GP Four Seasons, Gatorskins and Schwalbe Marathon Plus.
The SMP's are heavy but bombproof, as can be attested by many here and in the touring forum.

Expensive these tyres are, but well worth it to avoid flats, as well as their longevity.

When I do get a flat it's usually a sign the tyre's so worn it's time to buy a new one