Lots of folks on FT don't like linking to bloggers but check out milevalue's extensive discussions of free one-ways. Hawaii is a perfect location for adding on additional free legs to the beginning and end of itineraries.

Focusing on big sign ups is bassackwards. Most people hate miles/points because they can't use them-what you'll probably find if you pursue the delta route (limited low level availability and roundtrip only redemptions).

Avios will be very valuable for trips to the west coast (short distance).

United and AA will be great for longhaul trips with free one ways added on-you can redeem for one ways on each program which helps find availability (eg: AA outbound UA inbound).