Considering the chaotic nature of Nairobi (and accompanying sounds) it's important to choose a hotel that filters out those noices for a well deserved rest.
The Southern Sun Mayfair offers exactly that. It's a beautiful colonial hotel with amazing gardens. The rooms are spacious enough and are of a very acceptable luxury standard (although the beds are a bit hard for my taste..). The bathroom could have been better, especially the water was fluctuating from time to time (temp and pressure) but that was the only glitch.
Service is fast and welcoming and the food served in the attached Spur restaurant is actually of a good level (it's like an american steakhouse). Breakfast is served at the other restaurant and is of very good quality as well.
Overall; a recommended stay in Nairobi. It's not the best hotel, but considering the price it's def. worth the money!