This is by far my favorite website for finding accommodations. Not only does it generally have the best deals, it also offers free cancellations on most properties, meaning that I can change my mind at any time without it costing me a thing. If a fall in love with a place and want to stay longer, no big deal. If I find a new destination during my planning but have already booked hotels, no big deal. Booking also has extensive reviews on all its properties, something I always use when making decisions.
I will be honest with you, I don’t love Airbnb as much as most people. While I do occasionally use it, I generally reserve it for certain types of trips, mainly ones that involve renting a beach house. However, I do always check Airbnb when planning a trip, just to see what they have to offer. Sometimes the options are better than hotels, sometimes they aren’t.
While you cannot book directly through Trip Advisor, it is still a great resource. They have the most extensive reviews of properties and display prices from and link to all the big hotel websites, meaning that you always see the best deal (it is usually with Booking).
If camping is an option, I will always, always choose camping. It is cheaper, more fun (in my opinion), and usually way more scenic. If you go this route, check out my post about finding campsites.