Our house has an open floor plan...the front living room (aka grandkid's TV room), dining room, kitchen and den all flow together. There's enough space so the two TVs don't compete with each other but we could see what the grandkids were up to without much trouble. It worked for us.
Enter the walking/crawling Duo. First rule of business was buying the highest TV cabinet we could find so Lyss couldn't crawl in it and pull out
all the paraphenalia for the satallite system. That fixed the den but the other living room had a low TV stand so the older kids could work it. The Duo loved to work it too. That room also had a radiant wall heater we used in really cold weather. I shopped for toddler gates but they were only for a little wider than a single door width. I put dining room chairs across the doorway so I could hear the screach when the Duo moved them to escape but that meant I was never allowed to go to the bathroom unless another adult was in the house. Enter my hero, Chuck the solver of all carpenter problems (hehe) at our house.
While I was gone grocery shopping he screwed a large unfinished piece of board across the opening. Problem solved....big people could step over it, heat could pass from room to room and of course, it added so much to the decor!! I'm so proud.