The dollar is incredibly strong against the pound right now, so you can certainly aim higher than you normally might, but if you want to stay on the lower end, I’m a big fan of hub by Premier Inn at Kings Cross. It’s aimed at the hip traveler set, and it gives you a good sized, nice room at a low price, just steps from the big Tube station at Kings Cross/St Pancras. It’s not fancy, but I think it punches above its weight and we were very happy with our stay compared to another hotel that was posher but had a very tiny room. Budget without feeling budget, like JetBlue.
For something a bit fancier with more conservative design, we also enjoyed the Radisson Blu on Tottenham Court Road by Warren Street. Again, good Tube stop for getting to the West End, but you can easily walk it and be down there in 15 - 20 minutes.