We have different molding in different rooms. In our breakfast nook, the molding matches the molding on the kitchen cabinets and continues around the room. It is even a different color. This is true for any room with cabinets- the molding matches the cabinets. Our dining room also has different and fancier molding than the rest of the house. We did keep certain things consistent (the picture rail and chair rail wherever there was chair rail) in order to lend unity and cohesion to the house. I think that as long as you have a reason for what you are doing and a cohesive plan, you should be fine:

Kitchen:

Dining room:

Mudroom:

Rest of house:

beagles, what a gorgeous house!!!! where did you get your paneling and molding from? i'm feeling better about different moldings in different rooms now, thanks.
any thoughts on whether i can put a dentil molding beneath the plaster ceiling decoration for my dining room? thanks!

beagles, I love all the trim in your house. When are we are getting to see new or updated pictures? Curious, how much longer before it's complete?

threeapples, I would think you could put a dentil molding beneath the plaster ceiling decoration. It's hard to exactly determine what it would look like without seeing pictures of your ceiling, but I have intricate moldings with a mural in my great room ceiling and I think that looks fine and it is sort of the same general idea as using a ceiling decoration and molding:

I don't know where they got the trim for my house. I told them what I wanted and they acquired the lumber/trim pieces from somewhere. I know some of it came from someone in PA Amish country (all trim done by the mennonite cabinet maker came from that source).

A lot of it is built-up molding (like they took a piece of lumber and put it behind a chair rail piece to make it more substantial; and the molding in the dining room I think is four piece molding)

aries61, there isn't a lot being done to photograph right now. I had posted the granite, which was the last big thing we had done. Now they are doing grading, installing the septic, etc.- nothing picture worthy :( Next week, we have a concrete sink going in, more granite coming and hopefully more lights being hung so when that happens, I'll post pictures. We are possibly thinking completion some time in January, but that's not set in stone. Here's a blog that shows the most up-to-date pictures of the rooms: http://stonepondhouse.blogspot.com/

'Public rooms' (LR, Foyers, Parlors, 1st floor, etc.) classically had more ornate molding.

'Private rooms' (BR, 2nd floor halls, etc.) had much less ornate molding, and might even omit things like crown.

Sometimes public rooms (formal DR) had less than the fully public rooms but often still had pretty ornate molding.

Working spaces (kitchens, pantries) often had little to no molding beyond the baseboard (AKA 'mop board').

A first floor bathroom would often be reasonably ornate, with decoration being less with more private bathrooms.

All this can be adjusted, and the changes in house layout have an impact.

Bedrooms where often relativity small and less ornate with a parlor that was more ornate for at least the 'master' bedroom, and smaller bedrooms often sharing a 2nd floor large hallway room for their 'parlors.'

Unless you are trying to produce a historical replica, just do what appeals to you.
You have to live and be happy with it.

As long as there is some consistency of scale and style with the moldings, there is no reason they can't be different. But, if you are talking doing an elaborate 8" plaster molding in one room and a simple 2" cove molding in an adjacent room that would be disconnected. If the adjacent room is behind a closed door, such as a bedroom, then it would be fine, just as different or even wild carpets and paint treatments for private bedrooms are acceptable. Treat your public spaces like the one connected space that it is. You wouldn't use the exact same fabric throughout that space, but you wouldn't use a purple floral print in the kitchen and an orange stripe in the breakfast area and a grass green paisley in the foyer without something bridging and connecting all of those colors and prints. Mixing florals, stripes, and paisleys is fine if they relate in some way. Your molding is the same. It can be different if it all flows and works together.