We had better not remain here.
In that kind of case, it's best to make a trial of drawing up a budget.
It's best to put covers on paperbacks.
We'd probably be best off beating them to the punch before they notice that fact.
People who live in glass houses shouldn't throw stones.
Should I put this bag in the overhead compartment?
I think you'd better go on a diet.
You had better put the book back on the desk, for the owner will come back there.
I feel sort of dizzy. "You look pale. You'd better take a day off."