Lisa Vanderpump is riding high after the launch of her new Las Vegas hotel ... but some of her longtime L.A. businesses may not be in her long-term plans.

We caught up with Lisa, and while she made it clear TomTom isn't going anywhere right now, she admitted tough business decisions sometimes have to be made ... especially in California, which she says isn't exactly the easiest place to operate.

With more than 40 restaurants, bars and hotels under her belt, Lisa told us not every decision is an easy one ... and reading between the lines, it sounds like TomTom's future may not be guaranteed forever.

Vegas, on the other hand? That's where Lisa's putting her chips. She's absolutely buzzing over the opening of The Vanderpump Hotel, telling us Sin City is America's playground and the perfect place to keep expanding her empire.

Catch the full clip ... 'cause Lisa also opened up about her true passion -- dog rescue.