I'm having trouble right now trying to determine how I am going to get good letters of recommendation for grad school. I'm going into my junior year and I've been doing research under the same professor for almost a whole year (including a full summer). I know he will write me an excellent letter, but that is just 1 of the 3 that most grad schools require.
Like everybody else on this forum, I hope to get into top tier schools, but I worry that simply getting 2 more LOR from professors that teach my classes as opposed to advising my research won't cut it for a Stanford or MIT. At the same time, I don't want to ditch my current research just to find and ingratiate myself with another professor because my group is on the verge of a couple publications on which I'll be an author.
Hopefully I'll get an REU or something for this next summer and find a letter writer there, but there's no guarantee with those things. I have a strong GPA and I'm confident in my ability excel on the PGRE, but my school isn't noteworthy physics-wise, so I understand I need to impress with great letters also. Does anybody have ideas as to what I should do to get better letter writers? Should I seek out new research even if I like what I'm doing now? Or am I just being paranoid and professors of my classes will do just fine?