How do I eliminate that annoying wet spot on my lawn that makes it to wet for the kids to play on?

Wet spots on the grass are very common on LI.  It could be an easy fix or difficult depending on the circumstances, first make sure it isn't a broken sprinkler head or other plumbing issue, if it is a clay spot it can be fixed by conditioning the soil over time with Gypsum and lime, or drainage could be added with a simple 9” X 9” box or a more expensive and complicated drywell depending on the severity of the situation.  A bad clay spot will never feel completely dry.