I was there, umm, 19 years ago. A friend of mine was a missionary and we spent three weeks traveling the country. If I remember correctly:
They drive on the opposite side of the road.
Many of the people of Kenya speak a minimum of three languages; Swahili, English, and their tribal language. I would learn basic phrases in Swahili for communication.
Do not drink the water, use ice, eat fresh vegetables washed in tap water, or brush your teeth with tap water. Use bottled water for everything.
You must try the Indian influenced food. Samosas were my favorite. We would grab a bag of those and Coke's for the day and we would take off. Chicken Tika was memorable, too.
They had a great candy bar that I don't remember the name of. Umm, Krunchies? I ate at least one per day.
Nineteen years ago, their Coke still was made with codeine since they had no Food and Drug Administration.
Do not go on an animal safari by camelback. Your legs will never be the same. Take the jeep tour, or better yet, two-track it in a Mazda with the local waiter like we did!
Check with your local health center for the immunizations you will need. I had to have seven shots (or boosters) and took malaria pills for weeks before and after going. I still ended up in the ER in Mombasa. It was from drinking the water. I spent 4 hours in the ER and walked away with three different medications. Total ER visit, which I turned in to my insurance company and was reimbursed for, was $19.
I stayed here (north of Mombasa), right on the Indian Ocean.:
http://www.hemingways.co.ke/index.asp
Stayed here (north of Nairobi). Beautiful scenery with massive amounts of birds and hippos on the grounds:
http://www.travellers-choice.co.uk/kenya/baringo.htm
Stayed here:
http://www.ccafrica.com/accommodation-1-id-2-11/lodgeid-2-2
And here:
http://www.serenahotels.com/kenya/sweetwaters/home.asp
Sweetwaters, Kichwa Tembo, and the Lake Baringo Club were my favorites. I really felt I was somewhere different.
You must try these restaurants:
http://www.africanmeccasafaris.com/kenya/nairobi/excursions/carnivore.asp
This is in Nairobi. We took a cab, which was actually a car from the 50's and all decked out with red fringe all over the inside. It was quite an experience. Some of the meats on the menu that night were crocodile and wildebeast.
http://magicalkenya.com/dir.nsf/allbusinesses/Tamarind_Restaurant_Mombasa?opendocument&l=1
This is in Mombasa. This was where I had my 25th birthday dinner and the atmosphere was fantastic! Beautiful place!
If you can get to Lake Nakuru, I found it fascinating. The wildlife was incredible and the flamingos are so plentiful that the edge of the lake is actually pink when looking down from a bluff.
http://www.kws.org/nakuru.html
It's a beautiful country filled with warm and generous people. You have areas that are not safe and the poverty rate is high. Be prepared for that. Be prepared for bartering, also. The school children would often come running to talk with us. Watch for animals and very large potholes on the road at all times. There really was no speed limit and the way they packed the busses with people was simply amazing!
Again, this was 19 years ago, and for the most part, we traveled off the beaten path and stayed within my friend's village, so perhaps someone has much more recent information.