Everyone of these is a resource that I have used personally in planning and booking travel:

For detailed traveler reviews and ratings:

• TripAdvisor (highly recommended, especially for lodging)
• Yelp (put the app on your smartphone)
• Zagat Guide (the bible for restaurant ratings & reviews, particularly in NYC)

For finding hotels & vacation rentals:

• TripAdvisor (search rates on multiple travel sites at once)
• Quikbook (boutique hôtel specialists in North America)
• VRBO (Vacation Rentals By Owner)
• VacationRentals.com (same parent and search engine as VRBO)
• Outrigger (vacation rentals in the Hawaiian, South Pacific & Asian islands)
• Big Bear Vacations (Big Bear Lake, CA, vacation rentals)
• Book-a-Bach (New Zealand vacation rentals)
• Orbitz
• Travelocity

For finding air travel & ground transportation:

• TripAdvisor (search fares on multiple travel sites at once)
• Orbitz
• Travelocity
• Southwest Airlines (no penalties for one-way travel, no baggage fees)
• United Airlines
• Delta Airlines
• American Airlines