Can't have your cake and eat it too. Best case scenario is finding a tire that is average for both uses. I'd try something like a Michelin MS3. The other side of the equation is how worn is your tire? No tire is going to be good in the sand after you've been rounding all the knobs off on the gravel roads around the house.
I saw someone at Pismo Beach running what looked like a Dunlop 756 rear tire. He was holding his own against everybody with a paddle. I personally run that tire on hard pack and prefer it over some of the hardpack tires like the 739.
Another vote for Dunlop's 756.........designed as a soft-int tire, works well on int-hard too. Dunlop's newish 952 may be another choice too, perhaps a little longer lasting than the 756, and leaning a little more to soft......(not so stable when cornering on harder terrain)........ based on my experience.