**In my humble opinion, liftoff speed is another useless speed for most piston singles. Far better to raise the nose wheel (if flying a nose dragger) slightly, keep all eyes outside and let the liftoff happen.
Tis a pleasure when you get it right which will be always with practice. In a tail dragger of course it is even more important to keep all eyes outside and again, from a tail low position liftoff is automatic.**
Aussie Bob has this right. Piston aircraft should be allowed to "fly off" by placing them in the proper attitude, NOT ROTATED off the ground like a jet. If done correctly, the aircraft will simple lift upwards away from the runway in manner almost imperceptible to passengers. "Rotating" a piston is poor form and has dangers associated with it's use.