K.K.
I have traveled alone with my daughter twice. Once, I did not have the gogo kidz travelmate, (so I lugged a stroller and car seat along) and once with one. I love that thing! She rode in it and loved it, and all I had to carry was my diaper bag. Easy.
I didn't check the car seat and gogo, I pushed it right to the plane and they took it like they take strollers. I see another mama said she had trouble with the gogo fitting in the security thing. We did not have that problem.
I love love the gogo kidz. We travel at least once a year to see the in-laws, and it has helped us a lot.
Other travel advice: bring along a few toys and books that she hasn't seen in a while (take some away now, and pull them out on the plane- they'll feel new.) bring a few crayons and paper. and what all the other mama's say- bring lots of food!
Have fun!