Goldcliff/Red Barn hide - advice needed.

Once a month we take our daughter to a Ballet course in Newport and have just 2 or 3 hours to visit the wetlands whilst she is dancing. I have loved the Goldcliff lagoons - but ask for advice as to what I might see at the other sites in the area. Having only a few hours at our disposal I've been reluctant to try anywhere else. (I've visited the reserve centre of course). Any advice really welcome.