For me, planning the trip is entertainmentin the weeks/months before we go. I get to enjoy thinking of things we can do and working to get perfect times for ADRs, then working out our plans based on what we actually get (then reworking because I find out about something new or cool that I think we should add in). I get to think about how much so-and-so will enjoy a particular thing I've planned. Its kind of a hobby.
BUT - those plans are very different depending on the kind of trip we are doing. Our first trip with my kids I planned to the nth degree- wanted to be sure there was something for everyone and that we hit all the big rides and highlights. Character meals, fast passes, detailed plans about pretty much everything. It was fun, and packed full, and we did deviate from some of the plans as we went along, but I had contingencies in mind, so things went pretty smoothly. I had gauged our energy level pretty well, so we were tired by the end of the trip, but not exhausted.
I was in town for work and came in a little early - I had 2 days in the park by myself (I highly recommend this - it turned out that we had some tough news to deal with in the couple of weeks prior, and it was awesome to have time to process as well as some time to be unencumbered by responsibility and entertained.) I had FPs and a couple of ADRs (no problem enjoying a meal solo for me), but loved being able to change plans on the fly and run all over the place. I used SO MANY FPs- easy to get them for just 1 person.
DH and I also spent a weekend at F&W - I had some ADRs and FPs in place, but knew we would want to be more spontaneous and less tied to a schedule. I had lots of ideas about what we
could do, but it was a constant conversation about what we
should do next. We even (sacrilege) cancelled a FOP fastpass in favor of sleeping in one morning (to be fair, we had already ridden the ride a couple days earlier. Don't worry, we cancelled it well ahead - I enjoyed thinking about whoever magically had 2 FOP fastpasses pop up for them

)
So my uber planning still happens, how carefully I expect to stick to the plan just varies depending on the kind of trip.