I have a Play All button which appears automatically on the navigation bar when I enter my designated music (sub)folders. It will automatically disappear when navigating outside the music sub(folders).
Someone might find this idea cool so I've decided to present it here.
Because of where it appears on the navigation bar (just after the path box) it's not obtrusive and its appearance/disappearance won't look jumpy or move/displace anything.
Here is the code used in the button:
@hideifpath:!C:MyMusicFolderExample\* @filesonly @useactivelister Select *.(mp3|ogg|wma|aac|m4a|mp4|flac|wav|mod|xm|x3m|mid|sid) ContextMenu Open
ContextMenu Open works great with AIMP audio player. Others such as Foobar might require some different command.