I imagine that no one will agree with what I'm going to say here (eek!), BUT! I actually think the lighting is pretty spot on in Phantom Manor -- there are a few lights (especially in the wallpaper) that don't work, so I guess once those are fixed, it will be pretty spot on.
For me, I would get rid of most of the second half of the ride as is. Going through Thunder Mesa is cool and all, but it completely takes you out of the immersion of the ride. I'd have longer in the house and then a tour of the graveyard. Keep it dark. They can add some light relief through things like the card playing ghosts, singing busts, etc etc.
Also hoping they'll make it so it can have the Xmas overlay during the xmas period (I reckon they will). Imagine how amazing outside of the Manor would look with dying holly and garlands?! It would be epic!