I'm currently in the process of renovating a 1920s rowhouse, living there while we do. If your house is livable as is, I'd recommend considering not gutting it. Obviously this depends on personal preference, but the quality of the woodwork and plaster walls in these old houses is so good, if they've been reasonably maintained they're so durable. We've also found that our house is better insulated than we expected, we suspect due to the plaster and brick construction. Our plan is to not touch most walls. We updated a lot of the electrical, refinished the floors, and updated some plumbing without moving any fixtures before or as soon as we moved in. Over time we plan to make some exterior repairs, replace the kitchen cabinets and countertops and take out part of the wall dividing the kitchen and dining room, replace most bathroom fixtures, and add mini-splits for AC. It's a lot cheaper than gutting the house, but we also like it because it preserves the integrity of the home and leaves things be that have stood for 100 years. And I love our plaster walls and radiator heat. Just my two cents from a different perspective.