The six proposals that developers filed to build on the site of the Winthrop Square Garage in downtown Boston all have a few things in common: They’d all be the tallest in the Financial District, they’re all “green’’ — most boast LEED certification and other environmentally friendly features — and they’re all packed with some combination of high-end condos, office space, and hotel rooms.

But each has a little something extra to catch the eye of the neighbors who’ll weigh in, and the Boston Redevelopment Authority staff who will nominate a winner. We pored over the proposals (so you, dear reader, don’t have to), and found many unique ideas. Here’s a sampling:

Hold on to your napkins

In its proposal for a 58-story tower, Accordia Partners suggests an observation deck on the top floor and a restaurant on the 57th, with an open-air terrace. It wouldn’t be quite as high up as the dining room at the Prudential Center’s Top of the Hub. But it would be the highest point in Boston where you could be outside.

No deck, but a Great Hall

Millennium Partners, in its proposal, snubbed the BRA’s request for an observation deck, offering instead a “Great Hall’’ connecting Federal and Devonshire streets. Framed by soaring 65-foot-high arches, the three-story space would be open to the air in nice weather, closed when it’s cold, and filled with restaurants and cultural events year-round.

Living together in the sky

If you’re willing to share a kitchen, you, too, could live in the tower proposed by HYM Investement Group. Its pitch includes 50 co-living units, which might remind you of a nice college dorm. Apartments would come with their own bathrooms, but the kitchens would be shared. That keeps costs — and rents — down to more affordable levels.

It helps if you own a farm

Entrepreneur Steve Belkin plans to pack a lot of amenities into a pair of towers totaling 1.7 million square feet at the garage site and neighboring 133 Federal St. One of the most unusual would be a farmers market in the lobby, inspired by — and perhaps partly stocked from — Belkin’s own Lookout Farm in South Natick.

Helping out the neighborhood(s)

The development team led by the global construction giant Lendlease is offering to share a small slice of the proceeds from its $700 million project with nonprofit groups in city neighborhoods. It’s pledging grants to the South Boston Community Health Center, the Boys & Girls Club of Dorchester, and Operation Lipstick that would be equivalent to one-third of 1 percent of proceeds from the project.

Tower for the people?

The centerpiece of Trinity Financial’s proposal is a plan to make prices for 40 percent of apartments and condos in the building — 258 units in all — affordable to middle-income Bostonians. That would be three times as much affordable housing as the city typically requires in each development. If they can pull it off, the project could redefine “affordable luxury.’’

Tim Logan can be reached at tim.logan@globe.com. Follow him on Twitter at @bytimlogan.