For the second straight weekend, ho-tel heiress Paris Hilton flew 4,000 miles from overseas to visit ... Las Vegas. Which is just a few hours from her L.A. home.

The reason? Cy Waits. She's dating the businessman and nightclub entrepreneur based in Sin City - and going to great lengths to keep the new romance hot!

A week ago, Paris Hilton came in via a flight from Egypt, and over this past weekend, on a flight straight from Brazil. Says a source close to Cy Waits ...

“It sure looks as if the new matchup is picking up steam on their fourth weekend of togetherness. They are inseparable while here in Las Vegas.”

He and Paris Hilton went to Pure, where sister Nicky was hosting and celebrating beau David Katzenberg’s new MTV series The Hard Times of R.J. Berger.

Cy Waits and Paris Hilton are really hitting it off.

Later, Paris, Cy, Nicky and David went to hotspot LAX in the Luxor, where Shayne Lamas and Nik Richie, her husband and TheDirty.com founder were hosting.

“They’re taking it slow and sensibly,” one of Paris’ friends told me. “She’s happy, and that’s the most important thing. It’s not super-serious dating yet."

“Nobody knows where this might lead. I don’t even think they do. Paris is so busy with her launch of her new Tease fragrance inspired by [Marilyn Monroe].”

"They’re seeing each other and getting to know each other better. She thinks he is very sweet, considerate and caring and loves the fact that he’s self-made."

That's a great little dig at former boyfriend Doug Reinhardt, heir to his family's frozen burrito fortune, but pretty much useless on his own merit.