Hmmm, I've thought and I think naked princess peach would be a good start

I like open world play, but I still didn't care Galaxy was linear.

The only thing about it is once you complete 100% with M+L (6 days after I got it) It doesn't have much replay value, but then I would say exactly the same thing for most other platformers.

That's about my only complaint.  I think making Galaxy more open world would be a mistake honestly.  Open world only makes sense when you have extra content to make the exploring worth something and SMG is already brimming with content.

They should let you use the VC controller,or the GC controller in the next game, the wii mote wasnt doing anything special for me.

I would like the next Mario Platformer to take place in the Mushroom Kingdom again, and show a completely different approach to 3D platforming. Not because I didn't like the spherical design, but they should keep on changing the formula without destroying the feeling as they have been able to do it until now.

Add an enjoyable single player experience.

 i thought u didn't have a wii

OT: more exploring freedom 

more levels tougher enemies better story

I wish they would add more 2D classic platformer elements. Trying to navigate the big Bowser galaxies, was a very creative, and challenging approach to an old concept like running and jumping. I would love if they added more stuff like that. It would be nice to have some hidden easter eggs or secret levels too.