Hi folks,
If you've got young children, the 5:15 p.m. dinner is probably your best option. The Luau can last more than two hours, so that 8 p.m. dinner can easily stretch to 10:15 p.m.
The trade-off you'll make for the earlier time is that the show looks better at night. In the winter months, this isn't much of a factor, as it gets dark earlier anyway. During summer, though, it's a factor.
Hope this helps!
Len