The Hilton Hyde Park is a large triangular building that towers over the park. It's one of those ugly buildings from the 60's that maximized the space but not isn't aesthetically pleasing. Inside they have made an effort to renovate the rooms and they are actually very pretty. There are suites with balconies overlooking the park, but the noise from the traffic below prevents you from keeping the window open for too long. The place is well connected by public transport and there are always taxis in the entrance. The Heathrow Airport is on the same subway line, the Piccadilly Line.
The rooms are classic & non-smoking with internet access and a movie rental service, iron, desk, and are non-smoking.