I've used Meguiar's leather cleaner/conditioner on my new cars the last few years to clean the leather. I found a very soft bristle brush and use it with the stuff. Spray on, let it soak for a while, give it a good scrubbing with the brush, then wipe/buff with a terry towel. Amazed at the dirt that comes off onto the towel.
For fabric, headliners, and tough stain removal I like 2 products but I don't know if my favorite is still available. I used to love Simoniz "Dri-Clean" liquid. It came in a regular non-spray bottle and was the best stuff I ever saw in removing dirt/grease from fabrics, carpet, etc. But all I have found recently is a spray version by the same name which is nowhere near as good.
Here in Canada there is a Turtle Wax product line called "Ice" which is surprisingly good. I have the interior cleaner product which comes in a squeeze bottle and use ot on all the vinyl/plastic parts in the interior. Cleans well, leaves a nice sheen when finished.