Is it cheaper to book a multi-city flight?

Rarely. It is almost always cheaper to book a round-trip ticket to a major hub like Nairobi and then buy separate, cheaper regional tickets for your internal travel.

Should I use a travel agent?

Only if you are planning a complex safari itinerary. For standard flights, booking directly with the airline or via Google Flights is more transparent and cheaper.

Finding Cheap Flights to East Africa

To get the best price, book your flights 4 to 6 months in advance and aim for arrival in Nairobi (NBO) or Addis Ababa (ADD) rather than smaller regional airports. Use Google Flights to track prices and set alerts specifically for the months of May, June, and November to take advantage of low-season fare drops.

Set your hub. Focus your search on Jomo Kenyatta International (NBO) in Kenya or Bole International (ADD) in Ethiopia. These are the major transit hubs for the region; flying into smaller airports like Kigali (KGL) or Entebbe (EBB) directly from outside the continent is almost always 20-30% more expensive.
Track the low seasons. East Africa sees a significant price spike in July and August. If you can, fly during the 'shoulder' months of May or November. Prices for long-haul flights from the US or Europe can drop by $300-$500 during these windows.
Use the 'Explore' tool. Open Google Flights, enter your home city, and leave the destination as 'East Africa' or blank. Use the map view to see which airport in the region is cheapest on your preferred dates. Sometimes flying to Addis Ababa and taking a budget regional carrier (like Ethiopian Airlines or Kenya Airways) to your final destination is cheaper than one single ticket.
Check regional carriers. Once you land in a major hub, search for regional connections on Precision Air, Jambojet, or Air Tanzania. These smaller carriers do not always show up on international aggregator sites, but they offer flights between regional cities for $100-$200.

Is it cheaper to book a multi-city flight?: Rarely. It is almost always cheaper to book a round-trip ticket to a major hub like Nairobi and then buy separate, cheaper regional tickets for your internal travel.
Should I use a travel agent?: Only if you are planning a complex safari itinerary. For standard flights, booking directly with the airline or via Google Flights is more transparent and cheaper.