Roundtrip Flights: Various U.S. Cities to Hawaii (Honolulu (HNL), Maui (OGG), Kona (KOA) from $362

Steps:

1. Go to Google Flight search and enter your to/from cities
2. Click on the calendar for pricing (best fares will be highlighted in bold green)
3. Click on a "green" date to see available return dates
4. Use those dates and book on Expedia (usually $1 cheaper), Priceline, Orbitz, or directly with the airline