Booking last minute, especially using the many online travel sites, is a great way to pick up a holiday for a fraction of the cost. Being flexible and willing to take late night flights is also a great way to save some money on tickets.
One way to keep the cost of travel down is to look for hotels that are just outside of the main tourist attractions. These are often quite a bit cheaper than the hotels right at the attraction plus may be a bit quieter and more family friendly.