A rotator may give you access to a few more signals. However, if you have more than one TV connected, and there's a conflict as to which aim is desired, someone looses. Also, you need to be sure your tuners support 'Add-Scan' or 'Manual Channel Add', if not, you'll find yourself doing a very tedious full rescan each time you turn the antenna.
There are alternatives to a rotator;
http://forum.tvfool.com/showthread.php?t=820 &
http://forum.tvfool.com/showthread.php?t=2882
My preference would be to try an Antennas Direct DB8E + Antennacraft Y10713 + UHF/VHF combiner + preamp (Antennas Direct 'Juice' or RCA TVPRAMP1R). This combination of antennas provides much more flexibility aiming and has a very good chance of eliminating the need for a rotator.