Not sure what it means for the rev meter (tachometer) to rumble, but the car "rumbling" isn't too abnormal, especially on an automatic while it's in gear. It's normal for you to feel the engine through the car more when in D, etc. than in Neutral or Park.
An excessive amount of vibration at idle normally means some of the motor mounts need changed. The rubber inserts can be broken and over time the rubber hardens, so even if they aren't torn/broken they transmit more vibration.