I think "grande" will come before the noun when it means great and means big or large when it comes after the noun. http://italian.about.com/od/grammar/fl/Italian-Adjectives.htm
Yes, but in a case like this where the adjective is after the verb “è” how do tell which meaning? Is “large” the default meaning and “great” the exception? In which case is “Quel vestito è fantastico” (from google) the best translation of “great”? I think “great” is a casual, colloquial word and “fantastico” sounds more literary. Any suggestions how best to say “That suit is great” ?
I think you were thinking of "abito".