I have three recommendations already: one from my academic advisor for four years who later worked with me on my thesis, a professor in a different discipline, and my boss at the writing center who I also had for a class.
I could get another one from one of my professors I had when I studied abroad in Amsterdam. We're still in touch and she's said she'd do it. There are several reason I was thinking I'd take her up on it. I could show that I was academically serious when I was in Amsterdam--a city with a stigma. I could show how I interact with people from other cultures and maybe make up for a lack of diversity in other areas. And lastly, she could talk about this cool project I did and probably won't get a chance to talk about.
But--it might slow down my application because of the abroad factor. And I've heard that too many recommendations that say the same thing (how am I to know they won't?) can annoy the adcomms or work against you.
Should I go for four?