I lived in Nigeria nearly 3 years (2001 to 2004), and spent about 2 months living in Kano. I toured and took groups to Kano to tour, eat and enjoy this historic and interesting city. The Gidan Makama Museum is where you start any tour of Kano. The museum, in a series of Sudanese-style structures, is a wealth of information. You will be required to get a guide at the door; they are informative. The museum walks you through Kano history from the 9th to 21st century. The museum, which has recently received a face-lift, takes about 45 minutes to an hour to get through. The jihad period and the British invasion of the city in 1901 are really interesting. Another overlooked building is Gidan Dan Hausa, which is the Kano State museum. It was closed as of September 2004, but you can see the curator at the main house who can likely give you a tour.
In Kano do this: From Gidan Makama go to the Emir's Palace. You can take pictures, you need to know someone in the court or within influence to get in. You can however try to arrange to see the Emir come out to court in the morning. This is normally not too complicated. Be there for the amazing Durbar, twice yearly Muslim fetes, where thousands of horses and horsemen go on parade to pay homage to the Emir. Amazing sight.
Sights: Kurmi Market, one of the oldest in West Africa, is simply amazing. Get a guide at the market or they will simply find you. The Dye Pits are a must for indigo cloth at great prices. The old city has amazing mud Sudanese housing. Get a guide at the market to take you around the city to see what is left of the old city walls. The German Government was paying to have a portion rebuilt.
Hotel: Stay at the Prince Hotel, only place in town that is clean and good; almost too nice for Kano. Stay clear of the Central Hotel. Durbar Hotel was under renovation, a likely good choice. But believe me, the Prince is your best bet. In a pinch try the guest houses at La Locanda and Torona Restaurants.
Food: Amazing choices for Nigeria. My favorites: 1.) La Locanda (Italian) great atmosphere and food. Really some of the best pizza I ever had. From chicken wings to fine Italian and roasted meat dishes. 2.) Peking Chinese, Mrs. Lee is a great hostesse, food is acceptable. Their Sunday Brunch is best. 3.) Torona (Lebanese) amazingly good, but has been going down hill of late, mangement problems. 4.) SeeSweets (restaurant and bakery), nice spot with nice terrace, no alcohol. 5.) Calypso (Lebanese) at the Prince Hotel. Nice place with professional staff and excellent food. 6.) The French Club, need to have a member sign you in, place known among Nigerians who like to get away from it all. Acceptable, not really nice, but nice fish at night. 7.) Lebanese Club, great mixed grill and nice atmosphere. 8.) The Golf Course, you need a member to sign you in, has great roasted lamb and beef, as well as, cold beer and good conversation. Other places like the Indian restaurants are good, but not too clean. Nigerian places are good in Sabon Gari.
Note: Sharia law has really put a damper on nightlife and alcohol consumption in Kano. People tend to stay home more. For nightlife go to Sabon Gari, Christian quarter. Kano is fun, and there are cafes to hang out in and drink coffee and watch people in the "G.R.A."
Good luck and have fun.