I buy the stuff that's just peanuts and salt because it's tastier, but mixing it really is a chore. It's not hard to understand why the type with other ingredients exists.
Storing jars sideways risks oil leakage, but makes their contents easier to mix. Also refrigeration seems to slow oil separation.
I stir it when I first open the jar, then store it upside down in the fridge, which works great, I often just scrape what I need off of the lid, but I may try storing it sideways next, thanks.