Surfing is a fun activity that new users would probably enjoy. The sandbox region of the Welcome Hub is a beach. If there were a water region east of it with surfing waves and a small island, this could show new users how much fun it is to surf and sail in SL. There could be a surf board rezzer and a sailboat rezzer on the edge of the sandbox region.
Eventually, there could also be a couple water regions connecting to the Stilt Homes to the east as well. Give the newbies another incentive to explore beyond the Welcome Hub.