If you're looking for accommodations with a lot of room or if your family is bigger than 8 people, then a vacation rental may be a good option for your family.
TripAdvisor lists more than 100,000 homes worldwide. They even have a widget to help you compare vacation rentals vs hotels.
HomeAway lists over 215,000 homes in 120 countries.
HomeAway.co.uk lists apartments, cottages, rentals in Europe.
HomeExchange lists over 37,000 homes in 137 countries.