Flight:
https://www.google.com/travel/flights
you can choose from up to 5 starting airport and 5 ending airports to compare prices:
you can hoover on the calendar to see the best price date
search to see the list of options:
Pay attention to the airport and date:
Sometimes, they give you "Price Guarantee" if you book via Google(They lower the price for you if the flight price drops)
Southwest airlines have their own booking system:
Hotel
I use www.priceline.com to book hotel, car and cruise
Sometimes, www.hotwire.com has better price for hotels
You can even get better price for hotel if you use hotwire's mobile app
Car Rental
Priceline -can pre-pay or pay later with little higher price
Costco Travel - Need Costco account, no cancellation fee
Nationwide discount vendor - need Nationwide's discount code, no cancellation fee
Verizon discount vender - need Verizon discount code, no cancellation fee