When you guys say interior...do you mean like seats, main console/dashboard, door cards?
I've painted just my door cards myself using a flat black spray paint (duplicolor IIRC). Holds up pretty well, no chips no bubbles and certainly holds up to the regular shoe contact when going in and out of the car. The effect is also pretty good, looks OEM.
Most of the time, horror stories of chipping and bubbling and paint not holding is due to improper prep work. Quality of a paintjob is actually quite dependent on the quality of preparing the surface. The extra effort in making sure that the surface is oil and dirt free will pay its dividends.
Removing the door cards is usually a piece of cake. But I would imagine the dashboard being quite a tedious job.