One other suggestion for you...we use www.Holiday-Rentals.co.uk
and have had wonderful luck with apartments in Europe. They are typically half the cost and much larger than similarly situated hotel rooms. This summer, we are staying in listing 83270 which is in the 6th (at the bottom but close to the big park and subway- a plus when are traveling with children). Agree totally with Hank...4th, 5th and 6th are our preferred spots but that is a matter of taste. Apartment rentals work well if you are comfortable without the services of a concierge and are more independant style travelers. Having used both, we most definitely prefer apartments. Best of luck with your trip plans.