We spent three nights in Savonlinna Rentals. It’s an excellent base from which to explore. Their website has plenty of additional information about the area and practical advice about parking etc.
Easy contactless check in. The whole interior was virtually new. Excellent Wi-Fi. Two washing machines, two showers and three WCs shared between ten rooms. This was fine in practice. Some of the rooms have kitchens, otherwise there’s a shared kitchen with everything you might need.
There was a bit of a muck up with our booking, as the twin room we reserved had been remodelled as a single room after we’d booked. This meant a fold away bed on our first night and two different rooms in the other two nights. Bit of a pain packing and unpacking all the time but the owner made it as painless as possible for us and they were both nicer rooms than the one we’d booked so no real problem.