I found Alaska Airlines discounted prices while searching for best prices to Hawaii. All flights are within US, including Hawaii.
Validity: until 02.01.2017
Travel dates: 2017
I presented several flights and prices below, but you should check Alaska Airlines website for reservations.
1) Los Angeles to Portland $116 17-31.01.2017
2) Seattle to Walla Walla $136 24-31.01.2017
3) Seattle to Boston $256 17-31.01.2017
4) Honolulu to San Jose $398 07.02-27.02.2017
5) San Diego to Kauai $398 28.02-15.03.2017
6) Portland to Honolulu $470 22.02-14.03.2017
For accommodation I recommend you to search hotels on HotelsCombined as it aggregates all booking portals including Booking. You can find hotel reviews on Tripadvisor which is also great for searching best places to visit.
Hostelworld offers perfect budget accommodation for students, backpackers and low cost travelers.
If you want to stay with a local, you should rent a room, apartment or house on Airbnb. When you travel on Airbnb, you will get $25 in travel credit as my referral.
I suggest to rent a car from RentalCars or Alamo if you want to drive around. AboutAirportParking is offering parking in major US aiports so you can leave your car there.