Think Qatar. Like you I have lots of Avios Miles accumulation but now a lowly Silver. Frankly they are a better service for you & your Lady unless you prefer a London stopover.

1.You can now easily link m8 your BA Exec Club account into Qatar Privilege Club and readily transfer Avios across. If it doesn't work out you can easily transfer then back too.
2. From there you can easily put in a variety of US outbound airports from the QR network and choose to fly to Nairobi to meet your Safari Connection.
3. I see QR are putting on *2 on certain routes in both Cabins at peak dates so think clever. There are plenty of African destinations in the QR network to fly to in their excellent Business Cabin and then fly inbound to NBO direct from there if the AVIOS at * 2 is too expensive.. Think Zanzibar / Kilimanjaro / Cape Town / Addis Ababa / Mauritius / Seychelles. This does mean you travel earlier so I don't know if this compromises if you are still working, luckily I am now retired from Rat race and have time. You naturally have the cost of a one way into NBO yo meet your Safari trip and African flights are not the cheapest, Ethiopian & Kenya have great regional networks though.
4. Alternately and this is not the better option, could you do " cough cough " do the joys of American Business ( God awful service ) into anywhere in Europe and then Qatar onwards into NBO.

Enjoy your Safari. We both love Kenya and I hope you get to the Coast ( Malinda / Mombassa ). alternately Zanzibar NE Coast or Pemba Island. Uncle Bill Microsoft has his place NW Zanzibar!

Great for Scuba / Snorkelling but I got burnt so bad as in water for too long!

AsanteSan as we say in Swahili!

My wife wants me to BURN $ seeing wild dogs in Botswana. Only 2 0r 3 VEERY EXPENSIVE camps, so fending this off currently! I have tempted her with OZ and a NZ cruise and like you need to get the !@£$ seats both ways in Spring 24 !

Cheers