Jeff Bezos, Lauren Sanchez Host Oprah on Superyacht, Still Pack on the PDA

Jeff Bezos and Lauren Sanchez got their own not-so-little 'Love Boat' floating off the coast of Italy, and none other than Oprah Winfrey is up on the lido deck with 'em!!!

The billionaires -- Jeff and O -- were shoulder to shoulder at the lunch table aboard the Koru ... his superyacht that's been cruising along the French and Italian Rivieras this summer. Sanchezos hosted Oprah and Gayle King Thursday for what looks like a fabulous luncheon near Capri.

As for what they were chatting about -- super-rich stuff, no doubt -- but it wasn't all biz, not for the hosts, anyway ... 'cause Mommy and Daddy couldn't keep their hands off each other.

After Oprah and Gayle boarded a tender to head back to shore (or to their own fabulous yacht), Lauren and Jeff were hugging and kissing before slipping into something more comfortable ... their swimwear.

Get used to this kinda scene aboard the SS Sanchezos ... we hear Oprah's just the start of a celeb parade aboard Jeff's ship. They'll be celebrating all summer with several groups of their famous friends coming aboard.