What is your building budget? I'd put the bedroom part on the middle of that wall, with the closets on the left and the bathroom on the right. Get rid of the hallway leading to the closet, which is a well-lit total waste of space. The closet is teensy compared to the hugeness of the rest of the MBR space. Agree that the vanities are too tiny, the narrow gap between tub and fireplace is going to be a cleaning and access nightmare, and get real about the number of times you are going to have a romantic fire-light bathing experience. It's cheaper to rent a posh hotel once a year. Stacking the bathroom over the kitchen shortens plumbing runs and lowers cost. If anyone breaks a leg, can they get around the bathrooms in a walker and wheelchair?

Do you have room to make that new entrance on the side of the house instead of on the front? I notice that you have "possibly another door" to the side, so I assume you do. If you could make the entrance there and move the powder room to the front, you could have the mudroom connected to the homework room. That means that the kids could access their backpacks easily, and homework would be more likely to make it back to school. You could also have the homework room open to the kitchen rather than the dining room, making it easier to supervise. It would also eliminate any "weirdness" from having two front stoops. Also, is raising the bottom of the window an option? If so, I would consider flipping the orientation of the kitchen so that the sink looks out that front window, with plenty of counter behind it for a little herb garden. This would allow you to open the kitchen up a little more to the back of the house where you entertain. I'd also close off the entrance to the kitchen from the foyer. Since you'll be bringing groceries in through the new entrance, you won't need it for that, and you won't have to worry about a mess in the kitchen being the first thing people see. It would also give you another wall to work with as you plan your layout. I'm thinking about something along these lines...

Thanks, I was thinking if we did fit in a shower & toilet, we'd definitely want some way to make it more private. Right now there's actually a wall that goes from above the garage door on the left to the kitchen doorway. I was thinking if we kept that, maybe we could make it a pocket door so that it could be open most of the time unless someone needed privacy? This is what the current layout is. We have the freezer in the room labeled Util. and it's so cramped and hard to open the washer & dryer.

Here's another idea: Your foyer is the right size to be a half bath. And since it's across from the stairs, it's also naturally positioned off what will feel like a little hallway. You mentioned that the stack for the upstairs bathroom is somewhere over the dining room (I think on the wall between the dining room and the front porch)? If so, then the plumbing/sewer lines aren't far from the current foyer. The front door could move to where the front-facing living window is. This is one of the few fenestration changes you could make to the front of an old brick house that would look right because it involves only removing the few bricks below the window. This doesn't require reframing (so it's not expensive structural work), and you don't need to add any bricks (which is good because new brick work never matches quite right -- good enough for the less-visible sides of the house, but not something you'd want on the front). You said earlier that your living room is so long that you don't use part of it, so it shouldn't be any issue to define a small section at the end of the living room to be your foyer. There's also a couple handy walls there for hooks or a bench or a wardrobe or whatever foyer-like amenities you might want. I suspect it'd be an overall upgrade from your current foyer, which is pretty cramped. Meanwhile, moving the bathroom frees you up to devote the current half bath space to the kitchen. The result is a MUCH more functional galley kitchen. Since all the working areas of the kitchen are in one line and the walkway is a generous width, you could easily have three people working in this new kitchen. You'll also be flooding both the kitchen and living room with light and creating a great cross-breeze by having a direct, uninterrupted line from the new kitchen door to that living room window that is closest to the library. The kitchen is where you'd be doing your only structural work -- removing the current bathroom walls (if those are even structural) and creating a new window over the new sink location. The kitchen sink in the galley hasn't moved very far from the sink's current location, so hopefully that'll be more of a plumbing tweak than a situation where you have to pay to completely re-pipe. You'd also be turning the current kitchen window into your new kitchen door (which, like the living room window conversion, shouldn't require reframing and therefore wouldn't be structural) and bricking up over where the old kitchen door was. You could leave the bathroom window as-is if it is above counter height and you're willing to forgo a storage cabinet to the right of the stove. There's also a possibility that the bricks removed during the living-room-window-turned-door process and the kitchen-window-turned-door process and the new-kitchen-window-creation process could be salvaged and used to feather in the patching for the old front door and/or the old kitchen door. As for the mudroom, I'd suggest you make the library a mudroom/library. There are two great walls for mudroom stuff right next to the library's backdoor. Even with whatever furniture you have in there for the library purposes, that room generally has space for the whole family to pile in and take off their winter things at once. And you'd no longer have people with mudroom business traipsing through your kitchen. In general, the above is a WAY better kitchen and a WAY better mudroom situation without an addition.