It took me nearly 150 hours of in-game playtime but I beat DQVIII completely (completed every single goal there is). The monster arena thing was great, although I didn't start doing that till very late in the game, so the only levels that gave me problems was Rank S. And it only took me 2 tries to beat Morrie.
And the Lord of the Dragovians is one tough cookie, I've beaten all his forms (plus his final form where you have to beat his previous 6 forms in a row to fight the 7th). But it was all worth it though, I got the complete Dragovian set for the Hero (which looks completely kickass) and all my characters will around the low level 60's so the 2nd time I fought Rapthorne, I managed to take him down in 2 hits and saw the happy version of the ending.
Great game overall, I definitely got a lot of milage out of it.
"God's in his heaven. All's right with the world." - Robert Browning (1812-1889)