A million dollars in a briefcase is almost the ultimate cliche, and accordingly diverse in its performances. Cliche is usually regarded as derogatory, but I must disagree--after all, where would we be without a million dollars in a briefcase? It is certainly cliche, but not in the sense that it is indicative of an absence of creativity; the briefcase by itself is totally ambiguous, lacking narrative, but it has strong potential to characterize any scene that it is placed in. In this sense the briefcase is more a character than a simple plot refrain.
For the other half of the brain: have you ever wondered if a million dollars would actually fit in a briefcase? These things are easy enough to figure out these days. The dimensions of US currency (from here) are about 6.1 x 2.6 x 0.0043 inches, and a common briefcase size is 18 x 13 x 5 which is enough space to hold around 17,450 bills. If each of those were hundreds, that would be $1,745,000. In fact a slim 3-inch briefcase can hold a million dollars. If someone really wished to avoid being cliche they could take the money in pennies, though it would be a poor choice; a hundred million pennies weighs just over 550,000 lbs, and all of them stacked would make a tower almost 79 miles tall.