A touring plan is a list of attractions set in the order that you will visit them, starting at a specific time of the day (usually rope drop) and designed to get you the shortest waits possible for each attraction. Touring plans can either be generic, pre-made and you just see the attractions that they have on their list, or they can be personalized where you hand pick what attractions you want, and they give you a plan to get them done in the shortest period of time.
In my experience, first off, touring plans I think are less necessary with the advent of FP+. Secondly, I find that touring plans are of MUCH more use to people who don't have a lot of experience in the parks. When you have spent a good deal of time in the parks (we've visited for 2 weeks each summer since 2008) you will have a pretty good idea as to what order to do things in, and the touring plans may no longer be a significant advantage to you.
In the past, I have used both touringplans.com, and ridemax. Of the two, I preferred the plans I got from Ridemax. The last few years, I haven't bothered to use a commercial touring plan. I schedule my FP+, and then just hit the park with a general idea of what rides I want to fit in between the FP+ times, and life is good.