Honestly I'd enter on the VWP and fly back to the UK after 3 months then fly back to the US to get 6 months. That's the easiest way but you could be denied re-e

Honestly I'd enter on the VWP and fly back to the UK after 3 months then fly back to the US to get 6 months. That's the easiest way but you could be denied re-entry if you can't satisfy the border agents that you don't intend to immigrate (return air tickets and other evidence helps convince them otherwise). With your funds though, I would have thought that you would qualify for B-1 especially if you book conferences in advance with breaks that span longer than the 90 days. If you apply and are accepted the B-1 then it's valid for 10 years and allows you to stay for 3-6 months.