We provide 3-20 functions to our clients, and to convince them to make them, we have n criterias (currently 4: Speed to Result, RoI, Perceived Urgency and Long term Goal Alignment) that will be given a subjective number 1-5 to see which is more important, which can be summed up to a total, and sorted after from highest points to lowest
Your goal is to set up an admin-page in which we can set up these kinds of sheets, one project (client) at a time.
For every function, we also want to say that it take a certain amount of hours if we (experienced) do it, or the client (less experienced) do it, lastly, a third time needs to be presented and summed separately that has nothing to do with the Gantt-chart however, and that is how much time a function will take to maintain recurringly every month (often nothing)
A function may though be depending on another function being performed first (a predecessor), so then the predecessor will have to be listed before its successor even if the successor has a higher score.
It must be possible to state how many hrs of a resource that's available per week and what the resource cost per hour is for both us and for the client if they would do it themselves.
When we've entered these functions, their score, which should be in-line editable after initial upload, a gantt-chart will be built automatically, with a timeline over the next weeks where both the time it would take us to do it in green, and the time it would take the client to do it in shadowed grey slightly underneath.
Currently we use excel to keep track of it, see the screendump in the image, but as you can tell, it does not show any gantt bars to visualize how long time something will take.