I make adaptive plans. It sets a direction for us to go, and then we adapt as necessary based on circumstances. On some days I arrange a default ride order and times we will see certain shows. But it is not written in stone - as things come up we work with it.
For me planning is not so much to get us to specific things at specific times - although sometimes it is - but to give me the information I need to integrate everyone's ideas.
For instance, last summer at DLR I found out about the DCA Animation Studios and Turtle Talk With Crush thru the DLR forums, neither of which we had ever done. Based on my research, I anticipated my kids would want to stay at the Animation Studios for 90+ minutes. I did plan for us to visit the Animation Studios on our second day, but not a particular time. Since no one in our family had been there, no one was excited about going there. So I suggested we try it, and we all went in, and the whole thing was a major highlight. My DS9 sat in front for TTwC and got called to ask Crush a question. We did everything there, and Sorceror's Workshop was also very popular. I finally had to corral everyone (including DW who was wrapped up in the sound studio area) after 90 minutes so we could get back to the hotel for a nap.
I did not plan the Animation Studios as a military operation at a particular time, but I did research it and had a basic idea of what to expect. To my kids it all seemed fairly spontaneous. Without some level of planning, we might have missed this fun activity.
One trap I occasionally fall into is while I am on a particular ride I am thinking about "what to do next". Whenever I find myself doing this, I always stop and force myself back into the present to enjoy the current ride or activity. If you find yourself spending so much time thinking ahead that you are not enjoying the present, you have overdone it and need to drop the plans and get spontaneous.