i just went on the suggested web site. it is ok as a beginning, in large part because as you go through the questions, you get to see a park take shape (pretty cool). but it leaves out more than it offers, so should not be considered an opportunity to complete a design, but to get some thinking started.
strangely, it leaves out a number of things
* tennis courts, basketball in the sports section
* sitting areas
* types of landscaping, ie flower gardens, shaded sitting areas,
* fitness walking path ... (just tree spaces or not);
* in the food-related section, there is no options for picnic tables only;
* there is no discussion of trash cans or no trash cans;
* playground equipment is not the only type of children's play space, for example one could have a lightly shaded area where grown ups can site and kids could play on a nice grass patch where they can be carefully watched.
and most peculiarly, it leaves out community gardening. i'm not implying that all parks need have community garden plots, but the design tool would be so much more valuable it if did indicate how to mix more types of spaces.
I would suggest that parks.nyc.gov get some diverse 'greeners' including community gardening professionals, landscape architects, community groups, ... as well as some novices -- to 'test' the program. Invite their comments, questions, etc. Folks who test it in NYC could be invited to some focus groups to share their thoughts directly.
Then take the comments to heart and improve the program. Its a good start and could be a better tool.