Travel Time from San Francisco to Entebbe by air?

Uganda? No clue. You wouldn't get a direct flight, though. They'd probably route you through England, maybe with a brief stop in France. Then you'd probably fly into New York. Then from New York you'd fly to San Francisco, possibly with another stop over on the way. All in all, you'll probably be spending an entire day on the plane... 18 hours +. When you go to book tickets, it will show your departure and arrival time (before you pay)... so just do that to get a definitive answer.

I punched it in at Travelocity.com and the shorted flight time I get is:
24hrs 48min - 2 Stops

Change planes in Seattle/Tacoma, WA (SEA)
Change planes in Amsterdam, Netherlands (AMS)