Having Rainbow Road 3DS back is absolute bliss. I don't think I like the music as much, but the track holds up in a spectacular fashion. The other returning tracks are great to play on as well.
However:
I agree completely. As time passes, I'm enjoying the Tour tracks less and less. At first...
For the life of me, I can't remember the layout for the Tour tracks each time I play. I haven't done them a crazy amount online but I should probably practice in Time Trials a bit because the complexity of the Ninja track and the changing layouts of the other two keeps messing with my brain. :P