I have recently spent 4 nights and 4 days in Casa Bella guest house. The rooms are large, comfortable, nice and clean. The staff are very friendly. Best of all, I had the opportunity to spend quality time with the owner, Indy, and his family, very well educated, hospitable, helpful, and cheerful people. I was even provided with a mobile phone, and taken to visit the Paradise Lost caves nearby, and Nairobi pubs in Westlands. I have to admit, this is by far my best stay in a hotel ever. I will definitely come back to Casa Bella when I am back in Nairobi.
In a word, go to Casa Bella and you will not regret it. The hotel is very handy if you are travelling for UN-related business.
Very well done Indy, please keep it up!