i would not write off BA miles they may be beneficial, if you have trouble finding flights with united to OGG you could fly united PIT-LAX for 12500 miles one way then fly AA using BA miles LAX-OGG for 12500 one way, this is 25k one way insead of 20k but if it gets you the dates you want for just a 5k premium it might be worth it, also you could add a stop over in LA for a few days and see some west coast sites if you might want. some times we need to think outside the box of avios are bad for longer flights