I can't answer your question on where to find a planning spreadsheet but I do remember I made one up for my first cruise. In my professional life I lived by the spreadsheet. That was fourteen years ago and I used it for that first cruise and that was it.
I had a spreadsheet that documented what my wife and I would wear each day and we used that for our packing list. It also included what activities we would do and what we would spend.
On our second, and forty more cruises later, the spreadsheet was no where to be seen. I gave up on it. It got a bit too regimented for my taste. Planning is needed but it is also easy to over plan your cruise. Especially if you won't deviate from the plan. Gee: I can wear these dress pants three times on a cruise and no one notices. Or you want to zip line but the spread sheet says you must go on the turtle farm tour. Plan packing and your activities but don't over plan and be prepared to throw the spread sheet out the window if need be.
Take care and enjoy,