+1 for the regular Schwalbe Marathons.
they area good tires providing reasonable
flat protection, mileage and balance between
rolling resistance and traction. Have 3000 km
on the set on my crosscheck, have ridden mostly
on dirt/gravel roads.
ps- please take my opinion on this with a grain of salt
as it is quite biased, biased because i've used the various
versions of marathons for more than 10 years, always
with good mileage and rarely a flat.