As someone who falls into that trap stay the hell away from any and every DQ casino. All the games are completely non-interactive except blackjack and poker and they don't let you bet high enough to be viable(And the later games you can't even play cards, insuring no fun is had). You're just sitting there slack jawed doing nothing for a hour while you wait for the rng gods to do you a solid. Even if you're doing something else at the same time it's just not worth it.
I am however, ALL about the dragon quest boardgame from III and V. They need to bring that shit back.
Anyway, 4ds isn't too hard, except for a surprisingly unnerfed cave near the town of women with lots of nasty breath weapons so you shouldn't have to grind much. But you can do it quick and painless in the shrine south of endor. Don't go in too far and the people in the wagon will still get exp and you can kill liquid metals there. Bring Alena with double attack earrings and you can try Mara turning into a dragon. I don't remember if that still works or not, it did in the nes version.
I only bothered because I wanted the hero to learn morph. Then when he wasn't learning it I looked up and found that someone at SE hates fun and they removed the spell.