8 of us are traveling to Waco in October. I am finding that flights are about 200 cheaper to fly from Atlanta to Dallas vs Atlanta to Austin. Is there a particular reason why? Also I was looking to book flights through Expedia but they don't allow you to book more than 6 at a time. Any other ideas on who to book through?
Book directly with the airline. Using an OTA like Expedia is fine until something goes amiss and you can't deal directly with the airline because you purchased through a third party. Always best to go directly to the airline and make your booking, even if you find it costs a few dollars more, which is not generally the case anyway.
If your top concern is travel time and not money, fly into Austin. Immediately east of the airport is the 130 toll road that will take you just north of Georgetown at 80mph speed limits. Leaving the metroplex out of DFW or Love Field is often times a traffic nightmare.