Is it bad for a 2006 Dodge Durango to sit idle and running for hours

The HEMI can handle anything including rippin toyota, ford and gm apart.

But your wife is a little cooky. I dont even get why she would do that? Very strange. She should think about the fumes that the HEMI puts off that whole time.

It is not great for any vehicle. An internal combustion engine runs best & most efficiently when under partial load.
When idling, a couple of things may happen: 1) the most severe damage may be to the connecting rod bearings. Because of the relatively slow speed of the engine, more pressure is exerted on the bottom center & top center of the bearings. The faster the engine turns, the load gets spread out more evenly over the bearing surface.
2)The other effect is not so drastic. It is an idling engine may not get hot enough to start the catalytic convert working or hot enough to run efficiently. It may also load up the catalytic converter with fuel that could lead to an early demise of the catalytic converter.
As u already know, it is also a great waste of money ( as the truck is getting exactly 0.00 MPG while idling ) & it is bad for the environment.

It wo not hurt the vehicle at all. It is exercise.

Your wife has issues, though.

Its nice to see that some people are trying to be environmentally conscience.

No.And why the H does she want to sit in the CAR in the COLD to READ?,,,,,,,,,,,,,,,

It ai not good for it! I am still puzzled... WHY? lol maybe you should turn the heat on in the house?