Ridemax absolutely has less value if you already know the parks very well. If you have a smart phone, I'd look into one of the ride wait apps, even to just start playing with it on days that you anticipate will look like your day. Ridemax predicts all the wait times for each ride (mostly accurately) and then just uses the shotgun approach to try several itineraries and give you the best one. Unless it's changed, it doesn't do fancy math or anything to discover the best schedule, but uses trial and error. So you could come up with a viable plan on your own.
Now, I did think Ridemax factored in Fastpasses; I know they have (or had) an option to either use your Fastpasses late or use them during their window. This was in 2009, and I still have the plans saved using FPs. You can also use the option for slower parties to (hopefully) avoid some criss-crossing.
In my experience, much of Fantasyland DOES get less busy a couple hours before closing on a late night--Snow White and Pinocchio tend to become walk-ons, and even during a very busy time in 2009 (one of the last days before blockouts of the Southern California APs) Mr. Toad was only about 10 minutes as midnight approached. I think they clear Peter Pan Flight for the fireworks shows? So if you wait until after the fireworks you can ride with a short line...the only issue is you have to wait until the fire marshall clears it, which could take a while.
They do sometimes get things very wrong, though; I'd forgotten that. I didn't have any wait time problems (aside from when I rushed to a ride, only to find it broken down, but that's not really Ridemax's fault). But they told me to do Tarzan's Treehouse at 11:30 PM. It closes that late at night (or at least it did in 2009) so I never saw it that trip. I emailed them and they just thanked me for the feedback and said they were fixing it (no apologies).
