Private jet group travel, e.g., National Geographic

I started getting brochures in the mail advertising package trips to various parts of the world, e.g., Africa, that include travel by private jet with nice lie-flat seats, about 40 people. Of course it is very expensive, but given how stressful and exhausting commercial jet travel has become, even in business or first class, especially for those of us who are older and fussy about comfort and health issues or when traveling to more remote airports, I have started exploring the group private jet idea for perhaps a couple select, blow-out bucket list journeys before I, so to say, 'kick the bucket'. Some combine air with land and sea.

Anyone done something like this? If yes, thoughts on the experience, pleasantness of fellow travelers, etc?