I hope I don't fall foul of any Fodors regulations by giving a mention to a new and very useful website for planning a safari:

www.safaribookings.com

They have links to tour operators but I found the 'country information' and 'parks and reserves' sections particularly useful, with info on when to go, what to see, weather and climate, getting there, safety, pros and cons about a safari in each county etc as well as videos, photos and maps.

In their own words:

A summary of what SafariBookings is and offers at this stage
- The first online marketplace where safari operators can offer their tours (making it a whole lot less time consuming to find the perfect safari).
- Over 60 safari operators already joined and offer 120 tours. We expect that by the end of 2013 over 60% of all major safari operators will be represented and our target is to have at least 500 tours.
- Over 2,200 user reviews written by people from over 50 nationalities and over 750 expert reviews written by 19 safari experts. Most experts are reputable guidebook writers working for publishers such as Lonely Planet, Rough Guide, Bradt, Footprint, etc.
- Over 1,000 high quality editorial pages covering the 8 major safari countries and 140 parks (the content for the parks of Botswana, Kenya, Namibia and Zambia will be completed before July 2013).
- Over 3,500 photos from leading wildlife photographers, including Michael Poliza, Ariadne van Zandbergen and Heinrich van de Berg.
- Once the directory of all major safari accommodations is completed in 2013, SafariBookings will be the biggest online safari resource available.