I think it depends on how confident you are in making your own arrangements and how much planning effort you are willing to put in!
We prefer to "do it ourselves" mainly because, as airline employees, our travel plans can be quite complicated (the joys of stand-by travel!) and subject to change at VERY short notice so we need to have direct contact without having to go through a third party. But I have only heard good things about Dream Unlimited (sponsors of this site) so that would be a good place to start if you want to use a TA.
Whatever you decide, have a great time!