Yea, that seems better... I was testing out .a'o and .e'u in my mind, testing their "contrapositives" to see which one seems most opposite of the English:
.e'u xamgu nicte - [Why don't you have a] good night [, eh?]
.e'unai xlali nicte - [Warning, caution, no] bad nights [, ya hear?]
.a'o xamgu nicte - [Hopefully it'll be a] good night!
.a'onai xlali nicte - [Oh no! It's bound to be a] bad night!
Anyhow, I'm sharing because this exercise helped me prefer .a'o over .e'u.