I like my cities dense and packed tight, so I'm always open to squeezing a new building wherever possible (especially if it's replacing a surface parking lot), including on the Fulton/Ionia/Louis "Triangle Island" lot. That being said, I think if there's any place where you'd want to put a pocket park, it's right there. It's a small block, so anything you put there would be by itself. And the fact that there's other pocket parks nearby - Rosa Parks, Civil War Monument, Veteran's Memorial - is why I suggested putting something interesting there, like a fountain or a big statue, to set it apart. Being a triangular block, it would have a captivating view from any street corner, and it'd be a centerpiece for the entertainment district. I'm not a surveyor or anything, but whenever I've gone by there that lot just looks too dang small to build anything bigger than a Taco Bell Express.
Now, that other lot across the street, next to the parking ramp - that needs to be built on. I don't see why anyone would rather have a park there instead of Triangle Island.
And let's face it, the guy on this thread who actually lives near there - John - still feels a need for more green space in his neighborhood. I think that's worth taking into account.