Can I shuffle play 2 playlists together?

If you want to combine 2 playlists, simply drag one on to the other. All of the songs from the first playlist will now be copied into the second playlist.

If you want to shuffle 2 playlists, simply create a Smart Playlist that matches/includes the names of each of the 2 playlists. Then simply play that 1 Smart Playlist on shuffle.

You can also put them both into a new folder, then select the folder to select all the tracks in all the playlists it contains.

Ooo - good idea since that will also reduce playlist clutter