IMHO, you would only want to stay one or at the most two nights in Versailles. You need to take the RER to get from Paris to Versailles. Versailles is too easy to see in one day to spend the night there (trains to Versailles are not every 3 or 4 minutes like the metro). If you must use HHonors points, I would stay at any of the central Paris Hilton hotels and just take the metro to the major sites. That way you can spend time seeing the Paris sites rather than seeing the RER.