Generally, I hear "shana tovah" or "l'shava tova tikatev" or "shana m'tuka" and not the whole greeting and blessing.
There are four forms. You guessed it--masculine, feminine, and then plural for each. You will need the last form (feminine plural) if you are addressing roomful of your female relatives, students, or army recruits. I mean, when else would you encounter an exclusively female group?
Should I expand this page to a wiki, so I wouldn't have to do so much typing?
לשנה טובה תכתב l-shanah tovah tikatev
tikatevi
tikatevu
tikatevn=something
next week i'a: may you be sealed for a good year!