For dusting/cleaning the dash, doors, and other plastic areas I use a California dash duster. Had the same one for about 6-7 years. Works great at getting dust out of the textured part on the dash.
Cleaning plastic parts I usually just use a damp towel. You could probably get away with watered down simple green if you need to get some gunk off the plastic. Watered down Woolite works well for little upholstery spots...I also like the Reslove stuff in the aerosol can with the build in scrubber for shampooing carpets, seats, etc.
As far as dressing the interior I'm a big fan of Vinylex (same company that makes Lexol) for my interior plastics. Gives it a little extra shine without the greasiness associated with Armor All. Also helps hide scuff marks on the doors and rear cargo compartment.