I'd not try to use Amplitube on an Acoustic Guitar Realtrack, except perhaps very occasionally as a nonstandard Effect.

Try exporting the single AC Guitar track to RealBand or your favorite DAW software, make a copy clone of the track and then try timeshifting the copy a few ticks down the timeline for a doubling effect. Experiment with differing amounts of the time slide, for you can get everything from Chorusing through Flanging that way.

The EQ plugins can be used to change the sound of the AC Guitar track very effectively by adjusting different amounts of High, Mid and/or Low Frequency boost or cut. Use it like a Tone Control.

Sometimes a wee bit of Audio Compression can help certain types of AC Guitar tracks, all depends on the mix it is sitting in, and your ears and taste, of course.

Phaser, Chorus, even Flanger plugins may be used to enhance AC Guitar tracks as well.

And don't overlook any Stereo Enhancer plugins, which may also bring out something clean but different.

--Mac