Also, try adding something unique to your listing. Take 5 minutes and write about the building, area, things to do in that neighborhood - stuff off the top of your head that would be useful to a searcher. That makes you the authority, will make your content more apt to be socially bookmarked and gives you some unique elements to the page.  Also try loading a video of the listing if it is yours.

I wouldn't build out elaborate content for the property listing pages. I would however build out elaborate content in my website blog about Manhattan real estate, where I discuss the market, types of housing, moving tips, renters insurance, etc - things helpful to the person looking to buy, rent or sell - and that you can keep on your site as evergreen content. Do that first before you start no indexing listing pages. Keep the meta data on the listing pages unique to your site. google knows catalog sites will have the same short description, etc. Your real traffic will come from the content you create in your blog that relate to the listings in your catalog. Then do internal linking from the blog posts to the listing pages. If you have an admin section or other part of the site you do not want people to find in organic search, then no index those....but I wouldnt tell google not to index my product inventory.

I agree. Do you have a blog on your site? If not, I would create one and load content there over the category listing pages. There are tons of real estate sites (catalog sites) that share the same listing content.

Just make sure you have unique page meta data and h1's. Then beef up your site with high quality content about your area, 800+ words each.

But I would not no index / no follow the listings pages.

I agree with Dean. You should stick with the format being used on your main site. Also, be sure to go into webmaster tools and verify both the www and non www versions of your site, then select the preferred version of your site as non www. I think you might have some link juice loss as well due to redirect of www to non www. So just link to what your main site uses and you will be good to go.