Emily, almost all Gate 1 tours are priced either "land only" or "with air." There are a few that only have the with air option, but most give you a choice.
Advantages of booking "with air" include that they will provide free transfers between hotel and airport. Disadvantages include the need to work through someone else when irregular operations occur. I saw this firsthand on a Gate 1 tour when our flight at the end of the tour at a small airport was delayed by 4 hours. This meant everyone was scrambling. Those with Gate 1 arrangements got home just fine, but it was just one more hoop to jump through. I was glad I made my own flight arrangements at that time.
Also, unless you are in a big hurry to book, I would make sure that you go online and sign up for their weekly special emails. For the last two years they have had a sale in Sept and a sale in March where they waive the single supplement for 4 days. This can be a big money saver. (saved $3900 last sale on a river cruise/tour). If they have this sale, you would learn about it in the emails. I also try to post something here if I can.