"w=sqrt(geff/r) which gives 1.8 Hz for 9.81 m/s^2 and a 3 meter radius"

Er, that 1.8 is angular velocity in radians per second, so that's 0.29Hz or just over a revolution every 4 seconds. Still fast.

As a table:

 G      Hz     RPM
1/10   0.09    5.5
1/3    0.17   10.0
1/2    0.20   12.2
3/4    0.25   15.0
1      0.29   17.3
1.5    0.35   21.1

I agree that the 'tidal' forces would be rather high at that radius, even being in bed and raising your head would be rather nausea-inducing at 1G.