As noted, the $1 bill costs more to keep in curculation than its worth, but the only way to get people to use the coins is withdrawing - gradually, if need be- the $1 bill from circulation & stating a date by which it will no longer be legal tender.

I don't expect to live to see the rational thing done, however- & its interesting that none of the Government-Is-Wasting-Your-Money crowd ranting about this waste of money.

As far as recognition of the coin goes, its a shame that instead of messing with the diameter, they didn't take a cue from the British £1 coin, and double the thickness while keeping the diameter about the same as a U.S. nickel, but its too late now.