This is a new design I'm working on at the moment.
It is, as you can probably see, influenced by the in-game UI. I want to make it easy to use, and having the same general layout as the game probably helps.
The screenshot was taken with a resized browser window, I did not resize the actual screenshot. It might look like you don't have much room for the map, but you really do. The building menu is about 400x400 pixels.
In the upper left corner, you will see a button to change languages, and buttons to go to the buildings and units pages. There's also a help button, which will open a help screen which explains some features of the tool (much like this very post). Below that you can find the options button. This will open a screen where you can save and rotate your map, zoom in/out, do the road check, place a town hall, and probably some other options I'm forgetting at the moment. In the future, this will also include the options to enable you to place same sized buildings on top of each other, and a way of placing roads like the game itself does.
A town hall will, by the way, be placed on the map by default, it can not be sold but it can be moved and placed in the 'storage boxes' (more on that later).
In the lower left corner you will see the building menu, which includes tabs to toggle between building types. You can minimize it by clicking on the down arrow.
Great buildings and special buildings will have a drop down menu below them, so you can set the levels/ages.
Just above that are the buttons to delete and move buildings and to add/remove expansions.
In the upper right corner you will see 3 buttons, each opens a window with information when you click on it. The top one opens the information regarding population and happiness, the middle one will show the productivity, and the bottom one will show the building statistics.
Just below that is the temporary building storage, which can hold 4 buildings.
Also, imagine a map (same as the current one) somewhere on the screen, haven't added that yet.
If you have any suggestions, or if you think I forgot a feature, let me know.