If you plan to limit your adventures to Kenya's capital city, make the most of the city center.
Organize walking tours of Nairobi with visits to local attractions, including the International Convention Center Tower, which is a great vantage point. Note that it is safest to stay in your hotel after 18:00 - the city becomes unpredictable after dusk.
To take your time to familiarize yourself with the city and appreciate the local parks and museums, as well as visit the local slums, you will need 2-3 days. A typical Nairobi city-tour type itinerary, including visits to 4-5 sites and lunch at local cafes/restaurants, takes at least 4 hours.
Since you've traveled such a long way to this country, we highly recommend supplementing the standard Nairobi walking itineraries with trips not only to the capital's National Park, but also to the outlying suburbs and other cities. The most adventurous travelers will appreciate multi-day tourist routes from Nairobi to Masai Mara, Naivasha, Rift Valley. Tourists are offered both road trips and unforgettable hikes.