I seem to have some strange grease and other stains near the tan cloth/upholstery next to the sunroof. What do you guys recommend cleaning the stain with?

Take a look at some of the interior cleaning products from Megiuar's. The trick is to never get the headliner damp or wet. Spray the product directly onto a terrycloth towel and blot onto the stain. Again, if you feel the headliner begin to get damp, stop. You do not want to loosen the adhesive that is holding the headliner to the roof.

this one?
Meguiar's G9719 Carpet & Upholstery Cleaner

You can use simple green....it's sold at any auto parts store. I'm a detailer

I use that for the carpets, but not the headliner. Excellent product for that purpose. But any APC like the previous poster said will do the trick, but of course you dilute it for whatever you're doing. I would use Meguiar's Quik Interior Detailer. But before using any product, have you tried hot water?

I used a lightly damp cloth with a small amount of soap. Worked very well for me.