Question First Time in London: Where to Stay for 4 Nights?

My husband and I are planning our first trip to England and will be spending 4 nights in London. We're looking for recommendations on where to stay. We want a place that's convenient for sightseeing, with easy access to public transport, but also somewhere that gives us a feel for the city. Budget-wise, we're looking for mid-range options. Any suggestions on neighborhoods or specific hotels that would be great for first-timers? Also, any tips on what areas to avoid would be helpful. Thanks in advance!