Normally, you shouldn't be able to see either. I haven't checked the installation on a 742/743 but think about it for a moment - you want the right nav light to be visible to the right but certainly not to the left, and it's out on the right side of the aircraft. How would you see it from the cabin?
The beacons and strobes are generally along the aircraft centerline, well out of view.
However, when descending through clouds, the strobe lights will reflect off the cloud and be visible indirectly by illuminating the clouds. In fact, so visible that the pilots will most likely turn them off since they reflected light is blinding.
I thought I was doing good trying to avoid those airport hotels... and look at me now.