I'm guessing if the whole album is from one person, then the album artists field should reflect that.. However If it's a compilation of different artists on the same album them it can be "Various Artists"
If what u mean is by the different in doing this vs checking the compilation box only is that it would set the tag and "tell" iTunes its a compilation vs just creating a pointer saying it is one, then it may be better just checking the box and leaving the field blank for various artists albums only .
There are two hints as to how Apple meant Album Artist and Is Compilation to be used:
View > Column Browser > Group Compilations and
View > Column Browser > Use Album Artists
Watch what happens in the Artists column when you toggle those two features.
If you're going to use Is Compilation then intentionally making the Album Artist "Various Artists" is somewhat redundant - you may be able to use Album Artist more effectively.
Take for example an album where there's one main artist who does duets with guest artists. To me, the Album Artist is the main artist - I can find all albums by that artist by searching/sorting Album Artist. Similarly, if I have a compilation featuring solo appearances by various members of The Beatles, I might make the Album Artist "The Beatles," since "The Beatles" won't be listed in Artist and might not appear in the Title. For classical albums, Artist may include the names of the conductor, orchestra, and soloists ("Emanuel Ax; Andrè Previn: Royal Philharmonic"). If you're a fan of the conductor, maybe you want to make that conductor the Album Artist for all albums in which he/she appears.
I also don't see the point to searching/sorting on "Various Artists" - there's just not enough info there to make that search/sort meaningful - ("contains 'various artists' and 'classical'" doesn't tell me much, considering how much mix-and-match exists in the genre).
I've found Is Compilation to be the most reliable way of ensuring that a particular album is displayed only once in Album View. It fixed a problem recently where a 15-song compilation was displayed twice in Album view - all 15 songs were listed in one "album" and 3 of those songs were grouped as a second "album" as well. Adding Is Compilation eliminated the duplication.