Although not the first casino to do so, it seems that The Orleans, Las Vegas is almost 100% on the TITO system.

Only a lone Silver Strike machine accepts quarters. It is the only slot machine in-use that accepts quarters. There are two "Pay Check" machines that use special aluminum tokens, but all other machines use bill validators only (for currency and TITO tickets).

Meanwhile, one is hard pressed to find coin buckets at The Orleans. In fact, there are more coin buckets (with The Orleans logo) at McCarran Airport than there are in the casino!

FYI,

Jim