Originally Posted by
WineCountryUA
And are the changed times greater than 2 hours from the original booking?
It's nearly impossible to change from a nonstop to a one-stop flight without a two-hour difference. Even if it somehow managed to come in right at 2 hours, the extra stop is a valid reason for a refund anyway.
OP: You can ask -- but can't demand; they can say no -- that UA put you onto the Hawaiian Airlines flight at no cost to you. Your other alternatives would be to find a one-stop flight with UA that you preferred, or to ask for a refund of the un-flown segment. As
WineCountryUA said, the exact size of the refund is difficult to know without seeing your fare construction. UA can tell you, but be prepared to wait on hold while they contact the rate desk to calculate it.