#1: World Book:
I looked up llama because I have sheep and use them for protection. It was interesting to find information for the natural habitat of these awesome guards of our sheep. School edition uses easy to read language with limited information and lots of pictures and with videos to visualize the critters.
The Student Edition has more details with great videos to give a 'real' feeling of the animals. The links are great to send students on adventures into other resources for useful information on research  for reports.
World Book Advanced was like an adventure! It is hard to stay focused on the questions to be answered because there is so much to explore with the left and right links. There is a lot of basic information about the subject and the people; then one can advance to articles about various topics of interest in that country.
World Book Discover is great for teachers like my friend Jayni. She teaches foreign students English and helps them with citizenship and learning to help themselves here in America. To read an article and listen to it in their language is a help to them and then by listening to the words pronounced in English they can learn proper pronunciation more quickly. This can be a great aid to their whole family who is learning to speak English. A student of a foreign language class can pick up the language more easily. It was fun hearing the words in Spanish and French that I learned in school but I never have use of.

I have major catch-up to do so I am pulling one of those college all-nighters, so here goes!

Can't get my login right for #2 but I used this a lot when I was a librarian in Edgemont but will move on to #3 for now. I also help my friend Jayni in using it for her foreign students at the college she teaches at in Colorado.
.
#3: SIRS
Online SIRS is awesome! Very useful and easy to move around in for research papers or reports in any area just by using a subject and have all the information right there with any other related newspaper, magazine articles, graphics, or website  noted. There are so many options as far as reading level and learning style and interest. Teachers could easily use this for practice and challenges for students.
In Curriculum Pathfinder the Language Arts gives so much information with the websites, articles from magazines, and documentation and covers so much for use with teaching students and helping with practice in test areas. Students will be able to chose from a variety of information and from many ways it is presented.
Discover is very teacher friendly with the ability to use the three graphic organizer charts with varying degrees of difficulty. Suggested subjects help explore and define areas and focus more individually with students working at their own pace or ability. There is a lot of information available on countries and the maps would be useful for any study on any level.
Researcher has so many resources but the ability to narrow a search was useful since there are too many options! The over view of a topic is useful in this decision making process, as well as the pro and con section to see both sides of an issue. This would be useful to teachers for practice in many areas or for assignments for their students.