^From what I know of FotP membership, they're very little suburbanites. But they are mostly lakefront residents, to be sure.
Their lodestar principle is for citizens to have some voice in how Chicago parks and forest preserves are run. Secondarily, they would mostly say that parks should be used as parks, not as private building sites or private festival grounds.
For many years they have opposed that Soldier Field parking lot, and
have pointed out that it was the city that reneged on its promise to remove the Soldier Field lot.
Like any small nonprofit advocacy group, they have to pick their battles, and they've also been working to be more representative of Chicago's minority communities, communities that may have different priorities—like being able to park when they take the family to the beach. So they backed away from a fight over the new 31st Street parking area, and famously backed down from opposing the Obama Center.