I might white wash the brick to give it a more uniform look and keep a nice range centered in that arch. I would then move the fridge to where you now show the microwave because if you were to put it on the sink side of the stairs, it would be hard to access.

If you have the width, An open shelf island might be nice as well as handy.

doesn't appear the microwave location will really allow a fridge. I think I'd show them/encourage them to get a french door/bottom freezerdrawer fridge...[cabinet depth]and center it in the brick arch.I think they'd love it. Move the range over to the opposite wall and probably get above range microwave unless they are opposed to that. The area of microwave with the bulletin board/catch alls and papers/etc looks about18-21 in deep and 30 in wide. do something there with tall storage/perhaps with a bit of counter for toaster/coffee pot. if they'd want to keep a microwave there then create a niche at 54 in up from floor and you can still have counter for the other small things. there's a lot you can offer with vertical tall storage. With fridge only in the arch,you'd have some counter to the right for breadmaker to sit-it'll be displaced from it's corner if range moves across.You have a soffitt-do you have a goal of removing? Above the range, at least aim for a recirculating fan but perhaps a real hood could be vented up and then sideways out[but maybe not].

OP here. This will be a total renovation, and the brick arch will be removed. Total gut-reno, so please think bigger in terms of the kitchen layout changes. Thanks!

if you repositioned stairs closer to window then you'd get depth in kitchen space as the walk aisle shifts to closer to window.Proceed to remove wall between kitchen and dining room and run an island in the expanded footprint...but what is the budget and longterm goals here-first show the adjacent spaces and give a clue more about their expressed desires. With the elevation and stairs,you're constrained on that side,and if they don't want to incorporate dining room, then the existing footprint is what you have to work with.The bay window and wall with steps are not walls you can really do much without changing the steps.....that leaves the brick wall and back sink wall-so what are you hoping for?Where the layout doesn't allow a lot of changes,people can adjust their goals and do quite a bit of upgrading with the style, using materials/surfaces.

What is the layout of the dining room, and how much of it are they willing to incorporate into the kitchen? Would it make any sense to have the dining area and kitchen area trade spaces? Where do groceries enter the home?

Is an eat-in kitchen a priority, or would they happily give that up to gain more prep space?

Does that range have real venting now? Can it be moved and still provide venting?

You should post measurements of the TOTAL space to work with, otherwise responses will be limited to what you provided.

OP again. Answering your excellent questions, which I also answered by editting my original post - now I need to shamelessly bump this up!

Thank you, everyone for your great questions and suggestions! I realize that this kitchen is really constrained :(

To answer your questions:
Unlimited budget
Eat-in space (for 4, hopefully) is a big priority
Pantry space is not a big priority
Not willing to swap dining room with kitchen
Willing to move stairs
Willing to remove the wall between the kitchen and dining room
Dining room is not huge. They could steal about 1 foot from the dining room
Groceries come in from the garage, which is down the stairs and around the corner
There is a tiny vent for the stove, like a bathroom vent. It is vented outside, but I don't know the diameter of the ductwork

Thanks again, everyone!