Hi, ProjeQtOr ticks all the boxes. It integrates all the features that others have, and even more. Two level WBS : of course, ProjeQtOr does it, and even 20 or mode Levels if you wish !!! You don't have restrictions with ProjeQtOr; You can have projets with sub-projects, with sub-sub-projects (and so on) and each project can have tasks, with sub-tasks, and sub-sub-tasks (and so on). But if you want only two levels, you also can. Gantt chart ; ProjeQtOr also provides it but not only; You can have project portfolio, resource Gantt chart (not a real Gantt but very easy to read and very efficient to analyse resource planning). ProjeQtOr also provides real capacity planning calculation : you don't only draw a gantt chart, ProjeQtOr calculates it for you depending on the constraints and resources capacity (when resources are shared on several projects, it's not an easy trick). ProjeQtOr also calculates the critical path (which is in fact a critical chain in ProjeQtOr as planning is driven from resource capacity)
And all of this is easy to install, easy to use, and free.<p>Really, ProjeQtOr is worth a try.