When you begin vacation planning and see all the opportunities for various places you can book your travel, be careful and do your homework. I've noticed that some places you can book online are promoting free transportation to Disney resorts when you stay on-site in Walt Disney World. While it might seem a nice inclusion, this is something offered free by Disney to anyone who books a Disney vacation. It's not a promotion, it's a service that has been in effect for quite some time. But you may have to book this service on your own if you don't already have your flights booked.
I've also seen "no booking fees" and "no cancellation fees" being promoted. Be especially careful of this because when you book an airline ticket, there are cancellation fees! The airlines charge from $150 and up to change a reservation plus the cost difference in the ticket you want to change to. Most airlines now charge for luggage also. Except for Southwest Airlines, all other carriers charge from $15 to $25 per checked bag. And you have to pay that price each way for your luggage. Some airlines have a discount for pre-paying for your luggage online prior to departure.
Another caution about booking airline tickets online is to make sure when you enter your name, it is exactly how it appears on your driver's license or passport. If not, you may not get on that flight.
New TSA security measures also require you to provide your birth date and gender. This is so that regular passengers don't get confused with those on the government's "Do Not Fly" list.
While the Internet is a great resource for vacation planning, I've had quite a few people recently come in and tell me that it was too confusing to book their travel online.