Never stay in old buildings at St-Petersburg: it's cold, humid and problems with hot water. My apartment is in modern house with high ceilings, own steamshop (always hot water, hot battery). You will feel warm and comfort.
There are all necessary technic, dishes, linen. Good double bed, sofa, strong Internet, silence, safe area with highly developed infrastructure, security at the entrance. If you look out from the balcony, on a fine day you can see the dome of St. Isaac. Nice to meet you!