Use their Telekinesis beam.
Have them grab themselves with the beam, and rotate themselves to the desired orientation. No Potion of Flight required...
Oh, and as far as that eye ray goes?
New feat: Gaze on the Blink.
Requirements: Same as for Spring Attack
A beholder with this feat can briefly "blink" it's central eye, providing a brief time during which magic actually works in the gaze area of the beholder. As a standard action, the beholder can blink it's central eye, attack with it's beams into the area covered by the central eye, then reopen the eye, once again dispelling magic in that region. A held action may be used by an individual in the no-magic zone to use magic affects that are no longer than a single standard action during the timeframe. Any magic items that affect saving throws function normally for resisting the effects of the beholder's gaze attacks during the blink.
Have them grab themselves with the beam, and rotate themselves to the desired orientation. No Potion of Flight required...

Oh, and as far as that eye ray goes?
New feat: Gaze on the Blink.
Requirements: Same as for Spring Attack
A beholder with this feat can briefly "blink" it's central eye, providing a brief time during which magic actually works in the gaze area of the beholder. As a standard action, the beholder can blink it's central eye, attack with it's beams into the area covered by the central eye, then reopen the eye, once again dispelling magic in that region. A held action may be used by an individual in the no-magic zone to use magic affects that are no longer than a single standard action during the timeframe. Any magic items that affect saving throws function normally for resisting the effects of the beholder's gaze attacks during the blink.