Topless yet tasteful, L.A.'s new double-decker buses might dramatically change the way tourists get around, how they spend their travel dollars and the very look of Southern California's streets.

Introduced a year ago and recently expanded, the 16 double-deckers serve two separate circuits — one looping through Hollywood, Beverly Hills and the Mid-Wilshire area, the other spanning downtown. By spring, Starline Tours hopes to add a third circuit, serving the beach communities of Venice and Santa Monica.

For tourists and locals shepherding their guests about town, the old British buses with the open tops are a sun-splashed, whimsical alternative to the typical shuttle or bus. The double-deckers' hop-on/hop-off feature lets riders disembark to shop or dine along the route, then catch the next bus that comes along at 30- to 45-minute intervals.

Sarah Zahradnik of Australia found the bus to be an excellent way to see Melrose Avenue, Paramount Studios and the sights along Hollywood Boulevard. "I wouldn't pay any more than that ($30)," she said. "But it's a lot of fun."

The double-deckers, in bright red industrial enamel, amble along downtown in front of City Hall, or down Broadway, past the vintage palaces where Bob Hope, Duke Ellington and the Marx Brothers entertained audiences long ago. They rumble through the Fashion District, then loop around the new L.A. Live entertainment quarter, the burgeoning next star for Southern California tourism.

Today, running a tour service of vintage buses over a 40-mile area is fraught with logistical and economic restrictions, fuel costs, traffic and trees that need trimming (top-deck riders, be forewarned).

In a couple of test rides, the buses proved to be a wobbly, lumbering blast. Even people familiar with much of the city's history are bound to learn something from the narrated tour.

If you go: The double-decker routes do not overlap. People wishing to make the jump from the downtown loop to Hollywood must take a connecting 20-person shuttle that runs between the two loops every 90 minutes. The Universal Studios leg of the Starline tours is too steep for the double-deckers, so modern coach buses are used for that. But the 24-hour pass is good for that as well. For routes and boarding stops, www.starlinetours.com, 800-959-3131.