Yavin IV would be a good place for a Republic/Empire conflict -- the Sith could be trying to recover artifacts of Exar Kun or Naga Sadow, which the Republic would obviously want to prevent.
Kashyyyk has been suggested plenty of times, and I would have to agree. If the Infinite Empire really were responsible for the fauna of the Shadowlands, more secrets than a Star Map would have to lie buried within.
Telos IV might also be ready for us to return, assuming it's not already in the works. There's the HK-51 droid factory, Atris's academy and the holocrons contained within...plenty of story possibilities waiting to be used.