Sorry I meant to say

"But now my wife is having second thoughts about crown molding in the secondary bedrooms*."

I would think that if the hallways have crown, the bedrooms should probably have it, too. Sounds nice, finished and balanced.

Definitely go for it. Just be sure the size of the crown is matched by the height of the ceiling and size of room. Large crown molding in a small powder room with a 8' ceiling is overwhelming.

I've seen folks accent bedrooms with a different crown profile from the rest of the house. You could consider that.

It depends on the style of your house.

I'd love to NOT have any CM, especially in the LR, as I want that retro-modern look but not having CM wouldn't be appropriate in our house, kwim?

There are plenty of houses on GW and Houzz that have no CM whatsoever and they look great IMO.

But it all depends.

But I am not an interior designer. :-)

We put crown molding everywhere, but in the private spaces, we used one less pieces so it's not as beefy as in the public areas. Bathrooms deserve the same respect as the rest of the house.

There's no real right or wrong if she's worried about it being appropriate or not.

As has been mentioned, it's more about keeping what trim you install compatible with the overall style of your house, and keeping it in scale with the room. Economy comes into play as well.

My house is trim overload. While the house itself is colonial in style, my kids bedrooms both have wainscoting and crown. My son's room trends away from colonial, but it's what he wanted in his space.

My daughter's room, especially with her platform bed, probably has more raised panels than some houses, lol. So good and bad.

There is a builder around here that is installing crown simply so they can cover their always wavy wall-ceiling drywall corners. Some use crown to hide truss lift.

So crown can be decorative. Or it can be functional. Or both.

What size crown moulding as they make a 2 1/2" sprung or hollow back crown that is commonly used as a ceiling moulding or several sizes of solid crown which he may also be referring to?

I think it is a matter of taste and your house style. I put crown molding in all my bedrooms as I have a colonial and I feel it goes with wallpaper and a cozy look. I used a simple colonial 2 1/2 inch. I have none in my upstairs bathrooms as my tile goes to the ceiling. In my main floor I have a modern living room and dining room and crown molding would have looked odd, so I have nothing. However, in my hallways, I have a very simple but wide crown molding. I have a rather ornate crown in my family room and none in my kitchen as it too is modern. I do believe the mix blends. Contractors like it as it hides uneven corners and you don't have to paint in as exacting a way. So, just do what you like and make sure the crown and baseboard is your taste.

Crown was classically put in 'public rooms' (LR, DR. foyer, siting room)and omitted from bedrooms and 'non-public' rooms to save cost.

Wood crown was shaped by had using molding planes.

Plaster crown was 'run in place' and left either plain of embellished with cast (or even carved in place) details 'after the fact.'

You can do what your desire and wallet can sustain.