Cannot agree more with nink: M/B/B are a golden key to H/S/W not to mention any top 10 school. Actually, Wharton doesn´t like kids with 2 years WE in its class...
However, Big 4 and the like are still a very decent place to start your career. You can develop similar skills than in any top consulting firm and they are renowed worldwide (big plus vs. a boutique) so that you don´t need to waste your time explaining what you did in interviews.
My case: 3 years WE at Big 4 doing actual corporate finance /M&A (no due diligence stuff), attended reputed public undergrad and kicked asses at peers from private schools, now heading to NYC for CBS´12 with GMAT in the low range. No feeling inferior at all.
p.s. Full disclosure: top grades, 3 internships, extracurriculars and the CFA under the belt may have helped