We got to WDW on Mon 5/5 and this is our first trip as a family with my kids 8, 11, and 14. The last time I was here was over 20 years ago so it all feels new to me to. If my son and I hadn't educated ourselves via various websites and been keeping track of all the changes to fastpass+ we would have had a very different trip. This one has been great but a lot had to do with maximizing the system. I can't imagine coming with no plan, we would have been so disappointed, especially with it being our kids first and possibly only trip.
At MK on 5/6 & 5/7, both days were very crowded, but we we were able to do everything we wanted with a combination of rope drop, 3 fastpasses, and then adding a 4th and a 5th pass both days. AK felt really cramped on thurs 5/8 but HS wasn't bad on 5/9, more room to breathe. Today, 5/10, we were at Epcot and got to do all rides in Future World that we wanted and even scored a 4th fastpass for soarin tonight but only because you have to play with the system on your phone after getting it at the kiosk.
Since we aren't disney veterans it's hard to really say what the crowd levels are but MK isn't how I remember it and you definitely can't take a relaxing stroll through the park and expect to really experience much without planning ahead. I know that they have been 1-2 levels higher than predicted on touring plans each day, at least for the parks we chose (except HS, they were right on).
We are heading back to MK tomorrow for our last day and expect it to be really busy with it being a weekend and also Mother's day.