One of the major problems developers face are the zoning laws that different municipalities have in place, restricting the uses of buildings, says Joel Skylar, a principal at Boston-based Samuels & Associates. "Traditional zoning doesn't work when you're trying to mix uses because traditional zoning was created to separate uses," he says.

Skylar's firm is building Hingham (MA) Shipyard, a development with 200,000 sf of retail, 40,000 sf of offices and about 90 condominium units and what he points to as a the type of dense development that people prefer today. "People are looking for a more compact lifestyle," he says. "The suburban experience of the last 40 to 50 years, a lot of people are realizing, has its limitations."

Though many people prefer living and shopping in mixed-use environments, developers that are looking for quick returns might want to reconsider building the projects, says Richard Heapes, a partner at White Plains, NY-based Street-Works. "If you have to ask how long it's going to take, you shouldn't be doing this," he says. "You need patient money. You can't think in terms of three-year refinancings and you're out."

Mixed-use centers are often referred to as a newer trend, but Heapes sees it differently. "We don't think mixed-use is a new trend," he says. "We think malls and shopping centers are a recent trend to the way we've lived for the last 2,000 years."

For Douglass Karp, SVP at Newton, MA-based New England Development, a strong shopping component is the key to a successful mixed-use center. "We're often looking for the retail piece first, and trying to figure out the rest after that," he says.

But from a parking perspective retail poses the most challenges to developers, Karp says. Many municipalities require four to five parking spaces for every square foot of shop space, as opposed to three to four for offices and the one per room mandated for hotels.

For David Hall, an SVP at LNR Property Corp. of Miami Beach, FL, retail is almost a secondary consideration. His firm is redeveloping the South Weymouth (MA) Naval Air Station by creating 500,000 sf of retail, 2,855 residential units and other uses. But LNR might scale back the retail and not seek a major anchor tenant if it interferes with mix of the community.

Retail-heavy or not, Heapes says that mixed-use centers will likely remain a focal point in the industry. "I think ICSC should become the International Council of Mixed-Use Places because that's what people are interested in," he says.