At Dwell on Design's New Density panel, moderated by L.A. editor Frances Anderton, we looked at three very different local developments, all with their own definitions of community and sustainability.

First up, Bret Nielsen of Caruso Affiliate, famous for building shopping area The Grove here in Los Angeles. Their newest project, Americana at Brand, was commissioned by the city of Glendale, which is not too far away from downtown L.A. This massive development has 238 apartments and condos on top of ground-floor retail—and it's some of the nicest retail in the L.A. area—on beautifully landscaped grounds, and yes, it includes that Caruso signature touch, a trolley (in case your Armani bags get too heavy). This is all meant to emulate life in a five-star hotel, Nielsen says, including 24-hour concierge service, a pool with towel and beverage service, and room service from any of the restaurants for free (that could get dangerous!). This has attracted a diverse group of people who like the sense of community, from young N.Y. transplants who may miss living in an urban environment or older people who like having the services they can provide. For Nielsen, the focus is all about these amenities, plus, he says, people actually like the energy of living in a mall—the units right in the thick of it went first. While not exactly the Dwell aesthetic, he admits, the the units look posh, and there's got to constant entertainment provided by sharing your public space with shopaholics!

For Marty Collins, from Gatehouse Capital his work on the new W Hollywood Residences is specifically catered to the history and personality of the neighborhood. When it opens later this year, 135 units will share their living space with 300 hotel rooms and 100,000 feet of retail. One nifty feature is that it's very transit-oriented, there's a subway station, actually built into the development. But in typical collision between Hollywood Old and New, the transit area also shares space with a red carpet that runs right from Hollywood Boulevard. This huge anchor to the Hollywood neighborhood will be focused on bringing the entertainment and Hollywood business back to the area and yes, those hotel amenities, including dog-walking, will be available. The W Hollywood is aiming for LEED-Silver certification, with sustainable appointments in each unit, and lots of public art, by artist Pae White and others. Cutting-edge design is something that the W's audience expects, says Collins, so they have to deliver a high-end experience. In that light, one of the coolest features is a stunning rooftop pool with furniture designed by Daly Genik. The good news is, you don't have to share that with the hotel guests. That pool is private.

Bret Mosher's MKT Community Development puts the focus on community. His company takes mid-size buildings in the city of Los Angeles, perhaps in more underserved neighborhoods, and renovates them into properties that help gentrify the surrounding community. But perhaps the most exciting building Mosher owns is The Flat, a former Holiday Inn he purchased five years ago, which has residential units above and a restaurant Blue Velvet on the ground floor. And on the top floor is a rooftop community garden in a stunning structure designed by Alexis Rochas which supplies produce for Blue Velvet as well as for the residents. Mosher's units attract young professionals or students who like to move to urban environments, but are also happy to save money on not having a brand new residence. Not too many fancy amenities—although that garden is reason enough to move there—Mosher likes to design his spaces based on the interactions between the residents, who work together to make community living more livable.

Don't forget to follow our tweets straight from the Dwell on Design floor!