I think only you can answer this question. I had a 3.4 but wrote an optional essay on it. Yes my overall GPA was strong but I had a bad sophomore year (sub 3.0) followed by a two years of 3.7+. The problem was I had a few weak grades in important classes for b-schools (math ones). I did very well later on though in quant heavy courses like fluid dynamics and strengths of materials and did fairly well (48, 85%) on the gmat quant section. I had a true and valid reason for a crappy sophomore year so I wrote about that. This I think added to my show of growth not just academically but focus wise and probably helped.
That said I think a 3.4 with terrible english and humanities electives is a lot better than math. I think my math is what sunk my chances at GSB since it has such a strong quant rep that a bad math grade scares them...MIT actually asked for some math grades so they obviously care more about those than other courses. That said a 3.4 is a very solid GPA and if you were a steady 3.4 for all four years and no obvious weakpoints then trying to explain it will be like trying to explain a 690 gmat score.
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Kellogg Class of 2010...still active and willing to help. However, I do not do profile reviews, don't offer predictions on chances and am far to busy to review essays, so save the energy of writing me a PM seeking help for these. If I don't respond to a PM that is not one of the previously mentioned trash can destined messages, please don't take it personally I get so many messages I have a hard to responding to most. The more interesting, compelling, or humorous you message the more likely I am to respond.