We go in September at the same time every year and have been doing so for a while. So, I pretty much know what parks are good on what days. I also know we want to spend two days at DHS, three days at MK and one day at Epcot.
That being said, I still use the UG - it's never failed me. I check the crowd calendar for the time we are there and then make ADRs based on which park we'll be in which day. We are in WDW Sunday to Monday, so our "break day" - day we spend at our resort swimming etc. - is always Thursday. Arrival day is also spent unpacking and swimming/relaxing at the resort because we arrive early afternoon. We then have an early evening ADR so we can get to bed early and recharge for the next day.
We also follow a touring plan loosely based on one in the UG. Again, we've used it for years and it hasn't ever failed us. We usually get to ride everything we want several times in a day - utilizing fast passes when necessary. We adjust it when new attractions open, but that's about all the changes we make to it.
We also avoid EMH parks like the plague.
I'm a planner by nature and I love WDW planning, so although this may seem like alot, it's very soothing to us to know we have a good plan that will make our days run smoothly. We don't feel rushed or nervous at all during the days, because we know our system works. It makes for a great time.
Happy planning!