Im just back from Nairobi and stayed at the Central Park Hotel. As a regular traveller to Kenya i have to say this is the best value for money hotel in Nairobi.
2300ks per night with buffet breakfast or 2000ks without. If you take a woman back to your room it is 500ks extra.
Rooms are little small but nice and clean.
Location wise its a bit tricky to find right away but its only 1min walk to the Hilton so its very central.
Pierre on here found this hotel orignally i think.