Note that 2 hours is not the absolute limit, just the amount of time I'm aiming for the finish, actually about 1 1/2 to 2 hours. 8-10 people, fairly loose table starting with 100 chips. I was thinking of the structure below, anyone see any problems?

20 minute levels
1/2
2/4
3/6
5/10
10/20
15/30
20/40 (should be finishing around this level)

or should I got from 10/20 to 20/40 to 40/80 if needed?

Also is 20 minute level good, or would you go 15?