If you just want a real stable bike that's hill friendly, just get any ole touring bike.

Id recommend the Surly LHT, the Trek 520, the Marin Four Corners, the Fuji Touring, the Raleigh Sojourn, the Jamis Aurora, or perhaps even the Bosanova.

They all have longer wheel bases. Of course, that's to be expected with touring road bikes.

Good Luck!