[Note that in the examples that follow, all quotes, single and double should be straight. It is wordpress that makes them look like left and right quotes!!]
The XFCE4 desktop is known as a lightweight, fast, functional desktop, yet it has many features. It has a Desktop Settings Manager which calls a number of applets, not as complex or as many the KDE Settings Manager, but all that most people will ever need. There are a number of Panel apps that can be added. The Launcher is the most flexible I have seen, it can appear as a single icon to launch one program, or as an icon with a small arrow, which can have a drop-down menu, and this is done simply by adding more than one program to the Launcher. The top launcher will be the main icon, and if you want the program to re-appear in the drop down, just add it again.
As you can see from the screenshot here, I have put all parts of LibreOffice onto a single launcher.