I lived in London for about 38 years. I can't tell you much about hotels, but would recommend you work out the stuff that interests you most and find somewhere close to that then branch out, cos travelling around London can get a bit arcane. Buses are frequent but traffic is terrible, most stick to tubes and trains or even, if the weather is good, a boat down the Thames, though that's more for enjoyment than actually getting anywhere. Euston station and Kings Cross are useful hubs towards the northern part of the city, the latter used to have a rep as a pretty dodgy red light district after dark, but I think they have cleaned it up. Victoria's good for the southern part, and Charing X is good for the centre. In general, expect to pay more for accommodation as you go West.