A special dining event! Use Lucy Larcom Park or another canalside space to set up tables for one evening. Downtown visitors may order a special meal from one of several participating restaurants, and a waiter will bring the meal to the canalside table. It would be much like “Savor the Summit” Grande Table (see link) but on a smaller scale.
This would bring additional exposure to downtown restaurants and to Lowell's underutilized canalside space. It might inspire more use from the former Sun printing building. People may try a new restaurant if it's in a fun new context and want to visit their bricks-and-mortar establishment if they like it.
This has actually been done. http://www.tlfwf.org/
My only complaint was that one or two of the food trucks had generator motors that were so loud that they completely ruined the mood.