A new generation of dining entrepreneurs is ushering in a restaurant renaissance in Chicago, and its ranks include the sons of the man who’s dominated the industry for nearly 40 years: Richard Melman.

R. J. and Jerrod Melman in June 2008 opened Hub 51 in Chicago’s River North neighborhood and last May launched La Grande Orange in Santa Monica, Calif. And they’re thinking expansion — a hallmark of their father’s career at Lettuce Entertain You Enterprises Inc., the Chicago-based, $350-million-revenue restaurant idea factory that’s spawned 150 eateries since 1971 under nameplates including Maggiano’s Little Italy, Shaw’s Crab House and Ben Pao.

“The bulk of what we do will be here, even though our dad has covered the territory,” Jerrod Melman, 27, says of the duo’s plans to open more eateries. “But we think there’s still new fun things to do.”

If the Melman brothers really want to inherit their father’s crown, they’re going to have to compete against a host of other restaurant entrepreneurs in town — many of whom learned the business at the elder Melman’s side. Chef Michael Kornick, founder of mk, is one Lettuce alum; chef Scott Harris of the Francesca’s chain is another.

Even restaurateurs who never worked for Mr. Melman acknowledge his influence. Billy Dec, whose latest venture, Sunda, opened in February, says he’s tapped Mr. Melman for advice. And Rick Bayless recalls that when he and his wife, Deann, opened Frontera Grill in 1987, they borrowed from Mr. Melman’s playbook — particularly on matters like pricing and service. “They set the tone for all that stuff,” Mr. Bayless recalls. “We paid close attention to Lettuce.”

The new generation will define dining in Chicago, and big bucks will accrue to those who devise winning formulas like the ones Mr. Melman cooked up. Indeed, he made Chicago a center of restaurant innovation, and the new guard’s success will determine if the city keeps that status.

Other local entrepreneurs creating trendy dining concepts include the father-and-son team Jimmy Bannos Sr. and Jr., who recently joined with Mr. Harris to open the Purple Pig wine bar on Michigan Avenue. Donald Madia, Terry Alexander, Peter Garfield, chef Paul Kahan and Eduard Seitan recently opened Bucktown taco eatery Big Star. Collectively, they’ve worked on local hot spots including the upscale Blackbird and the cocktail lounge Violet Hour.

Meanwhile, Mr. Kornick and David Morton, youngest son of Morton’s Steakhouse founder Arnold Morton, in November opened the Lakeview burger bar DMK. And Frontera’s Mr. Bayless launched quick-service cafe Xoco in September.

Then there’s the competition represented by Richard Melman himself. He aims to open five restaurants this year, including a burger spot in Phoenix and a Mexican eatery in Las Vegas.

“I’m not about to retire anytime soon,” says Mr. Melman, 67.

All this activity is coming during one of the toughest times in the industry. The kind of expansion that Mr. Melman has achieved is more costly now, notes Darren Tristano, executive vice-president of Chicago-based food industry consultancy Technomic Inc. Meanwhile, he says, diners’ “flavor and taste preferences are evolving and changing much faster today.”

The key now is appealing to the mid-tier casual diner, says Bonnie Riggs, Chicago-based industry analyst at NPD Group Inc. For these customers, it’s “about good-tasting, quality, fresh food at reasonable, affordable prices,” she says.

Messrs. Kornick and Morton are aiming for the burger-and-beer demographic with DMK, and Big Star offers $2 tacos, $1 Schlitz beer and $3 whiskey shots.

“The one thing that played into (the idea) was the economic state of the country,” says Mr. Alexander, Big Star co-owner.

Mr. Melman, who opened his first restaurant, R. J. Grunts, in Lincoln Park with Jerry Orzoff in 1971, recognizes today’s challenges. “It was so much easier for me” to get started, he recalls. “It was so much easier for making deals. The public hadn’t seen as much as they see now.”

But Mr. Melman says he’s confident his sons can navigate the current terrain. In their teens, the pair worked in Lettuce outlets, at first busing tables and handling other odd jobs to get spending cash.

A key lesson they learned from their father is to “find your passion,” R. J. Melman says. “This is too hard of a business to be in if you don’t love it.”R. J. Melman, 30, cooked at numerous Lettuce eateries before he moved into management and helped open close to five locations, including a Joe’s Seafood, Prime Steak & Stone Crab in Las Vegas and Wildfires in Lincolnshire and Minnesota. He also was general manager of R. J. Grunts, which is where he got his name. Jerrod Melman worked his way up to managing Osteria Via Stato and R. J. Grunts. He also worked at other restaurant groups, including B. R. Guests and Union Square Hospitality Group in New York.

The duo began their new venture, a division of Lettuce, by opening two casual, mid-priced dining concepts. Hub 51 offers an array of dishes, from sushi to filet mignon tacos. They followed that with La Grande Orange, which has a menu that changes based on what’s in season at the local farmers market.

The Melman brothers say they’re not aiming to match their father’s restaurant-creation track record. “We like doing restaurants and we’re going to do them when we feel happy and feel we can grow them,” R. J. Melman says.