The one thing I don't like about Spotify Android is that I seem to only be able to Queue one song at a time. Anything (Playlist, Album, Artist, Track, Search Result etc...) should have an "Add to Queue" item in the long-press menu.
Updated on 2018-06-15
with the latest mobile App Updates, that should be implemented.
If you can't queue an Item, please create a new Idea for it after searching in the Ideas Exchange. 😉