In my opinion, get the biggest stove that you can fit in your opening. You can use fans to disperse the heat to other rooms. But you can't create more heat than what a small stove can do when it's maxed out. Better to have the capacity and not need it on warm days. I got the biggest unit I could fit, even had to make a little extra room and I'm so glad we did! We have an Osburn 2400 insert. It sticks out a bit from the fireplace which gives off a big amount of radiant heat. And the 130cfm blower pumps out a ton of heat when it's on high with a big load of wood. Also a larger firebox will give you more coals to start over with after you wake up in the morning. Our stove hasn't gone out since early November. On warm days (50-60*F) during the day we just toss in a single log every few hours and have the blower on low. That maintains a good bed of coals, and puts out enough heat to keep things warm. In the dead of winter we burn it hard, with the blower on high most of the time, and have to scoop out some coals at the bottom so we can keep multiple large logs in there to keep the temp up on it. But even down below zero, it still mostly heats our whole house.
Get the big stove, run it hard when it's cold. You'll be glad you did. Fans are cheap, and put one blowing out of the living room towards the kitchen and hallway with the bathrooms and bedrooms, and a fan blowing into the living room from the dining room. That will create a nice circular airflow which will spread the heat pretty well. And if you have ceiling fans, run them to help push the heat down to the floor. You'll be surprised just how much area you can heat with a couple medium sized fans and a couple ceiling fans to disperse the heat! Yes your living room will be a lot warmer than the rest of the house, but thats life with a wood stove. Should be able to keep all the rooms just off the living room very comfortable. That circular layout from living room to kitchen, to dining room, and back to the living room is going to be a big help.