for the flight you want to book directly through the airlines, that way if you have any problems you can change the flight or seating (you can't do that with Expedia) but you can use EXP to find the best routing and deals
Spent the past 3 yrs working for hotels and i will tell you. 3rd party company reservations may not always guarantee you a room. I had seen numerous people turned away that booked 3rd party and we were overbooked and those who booked through the hotel had rooms.
If you call the hotel directly sometimes we would have discounts for members of our rewards programs, veterans, and so forth. Depending on the hotel policy since we want you happy. You may be able to get price matching or an upgraded room. We hate losing business and will do quite a bit to make sure you are happy.
I stopped using those sites like expedia/travelocity ect cause ive found that they dont really offer much if any value prices. i use google flights to find the cheapest flights, book thru the airline and then book direct through the hotel or sometimes via the airlines website. Currently planning a 7 day(really 6) budget trip to japan with 3 friends so we'll be using airbnb for the most part as we plan on being in tokyo for a few days and kyoto for the rest.
I believe southwest has started doing routes from CA to HI now, may want to have a look at them?
Hotels and airlines would WAY prefer you book direct, because they have to pay a fat percentage to the Online Travel Agencies (OTA's) for each booking. The OTA's are like heroin, the providers are addicted to the volume of revenue-generating customers they get from OTA's that they can't/won't efficiently source themselves, but they hate the addiction because they give so much of that revenue up to the OTA's in return. Like, 15% or more. So when you book using an OTA, you risk achieving virtual pond scum status with the travel provider. If you want a better shot at perks, rewards, and great customer service, find the rates anywhere you want, but book direct.
Haven't used a travel site for flights in probably 10 years. I always find a better deal directly on the airlines website. I do three vacations a year and always start with Google flights first then check individual sites. For hotels travel sites usually have promotions. If you're looking for an all inclusive carribean vacation then this is where you would use travel site cheap carribean.com to book everything. The travel sites akso work well for cruises.