Welcome to Tropical Fish Keeping forum.
By "centrepiece" I assume you mean something a bit larger than those fish you have. This is not easy, as larger fish (such as angels) would eat the smaller tetras, or try to. Some suitable fish would be one of the dwarf cichlids, like the Bolivian Ram [on this forum, you can see the fish profiles by clicking on the shaded name of a fish or plant in posts].
You have an issue though with the bumblebee gobies. These are brackish water fish; they occur in estuarties in SE Asia where the water is approximately half salt, half fresh. In freshwater tanks they may "survive" for a time, but they will not be healthy. Adding salt to the water is not an option with fish like neon and lemon tetras, kuhli loaches, gourami and the plecos. Salt will damage these fish internally, burn their skin, and kill them.
I recommend you remove the bumblebee gobies, either to their own tank of brackish water, or see if the store will take them in exchange.