In addition to what others have said:
On the City Planner in EA, I like the 'Report' option. It provides info on just about everything being produced in the city. (I find it especially helpful when I'm trying to count the number of lvl 1 bldgs I have for FA farms. lol!). Expand the 'Production' section, then click on any resource and a window will pop up showing the buildings being counted for production. There are also options to put in things like culture boost %, number of collections made/day, etc, to get a more exact measure of what's actually being produced. You can play around with swapping different bldgs in and out to see the impact that has on specific productions. You can also play around with 'collections/day' to decide how often you need to be setting/collecting productions. While these numbers will not exactly match what you have in your city (explained in his 'FAQ's' section in the bottom right corner of the home page), it will still help with decision making.
The other items on the 'Tools' tab that I use are the Battle Simulator and the Research Calculator. I found the Training Calculator helpful in earlier chapters, but I don't use it anymore.
I don't have a need for the Unit tab, but I can see where smaller cities just learning the battle system could benefit from the various Unit comparison tables.