Travel agents are free
If you can pack food, eat out less.
Travel in groups for group discounts.
Check flight prices to see the difference in flying out of Lubbock and Dallas, as well as surrounding areas (Amarillo, Midland)
Try to fly with airlines who have free luggage.
Make payments a long the way.
Keep in mind age does matter. In most places under 3 is free in park enterances, under two is free for airline flights and under 17 is free in most hotels.
Travel during the off season, for families that would be during school, so plan a head and around the times children have breaks.
Shop around, look at several different options and find the best for you and your family.
Estimate on gas prices.
Keep in mind there are several discounts, just ask.