The Yellow Fever immunization is required by Tanzania nd Kenya when traveling between the two countries. However it is not required when coming from a Yellow Fever free country.
The cost of flying into East Africa is usually cheaper at Jomo Kenyatta International Airport (NBO). Local buses with Riverside Bus are available for transport to Tanzania.
Border crossings are never fun!
Namanga is the main crossing between Kenya and Tanzania, but if you have a choice of crossings we suggest Tarakea. The Tarakea border crossing is less traveled and much friendlier.
Air Tags are an invaluable item that we can't recommend enough to keep from losing your suitcases, pets, and children! When the airline loses your luggage, you can tell them where to look for it!