Both the Thor and Schron plans provide a distinct appeal for investors in the ESB, says Meister. “In both offers, the investors can remain in the deal, which is a very critical piece when evaluating the offers,” he tells GlobeSt.com. It's critical, he notes, since many of the buyers purchased their ESB shares simply to own a portion of the icon, with some families holding onto the shares for generations.

Still, it was not clear whether that's of interest to the Malkins, who had plans to create a REIT that would be anchored by the building, but hold 18 properties in all. That idea had been met with opposition from some other investors and a lawsuit, but the Malkins prevailed in court last month.A Malkin spokesoman declined to comment. If the tower goes into the REIT, it could be more difficult to purchase, the New York Post reports.

The Malkins, who reported in an SEC filing that they are considering all offers, as is their fidicuary responsibility, have other factors to consider before reaching any decisions, Stephen Meister, the attorney representing the Empire State Building shareholders who are against the public offering—and Jason Meister's father—tells GlobeSt.com.

“You can't compare a cash deal with a REIT stock without knowing where the stock will trade," he says. "Mr. Malkin hasn't done that yet but we hope he will.” For the investors, the senior Meister notes, without the REIT, “they own shares in one building as opposed to 18, which is good,” he says, “because they like the ESB.” Of course that's been obvious by their opposition to the REIT structure, but others “like the cash offer,” Meister says.

Neither Meister could say whether the Malkins have a preference for one deal over another. Stephen Meister did note that his clients could have a say in which deal gets accepted, "if they are put to a vote," though that may not happen if Malkin decides not to pursue any of the offers.”

As for the Meister father and son working on various aspects of the Empire State Building's future, both parties say it doesn't represent a conflict of interest.

The offers are unsolicited, anyone can make one,” notes Stephen Meister of the proposals put forth by his son. Adds Jason Meister, on what the two real estate professionals are doing, “It's totally separate.”