A GPA of 3.4 is near the center of the distribution for many of the elite and transelite schools and thus there might not be a great need to offset it. However, this depends on the degree, the degree-granting institution, and the classes that led to low grades (if any).
Carnegie: "For students entering the MBA program in 2003, the average was 3.35."
Emory (2 yr) "Average GPA: 3.4"
Penn: "Average GPA: 3.5"
Duke: "Average undergraduate GPA 3.39"
On the other hand, the GMAT is nearly in the far left tail at several schools including Duke, Penn, and MIT.
Work experience and designations/certifications help offset lower scores and grades to some extent since they demonstrate "working knowledge" of business.