Anti-Numb-Bum measures

With two big rides coming up I'm a bit concerned about my comfort. As I normally start getting a sore coccyx, and numb in the general bum area, around 70 miles I thought I'd better invest in a comfortable seat add-on.
I researched and AirHawk came out on top, not cheap but if it does the job it will certainly be worth it. 300 miles to Ypres on 29 May and the 500 mile sponsored ride end of June.
It's recommended not to blow up hard but to allow some movement so air will move between the air cells of the comfort seat. It comes with straps to fix it to the seat so I'll do that tomorrow.

Can you believe what came second to this, in the research, was those beaded seats. I've only seen them in cars but you can get them for bikes too.