For Sunday - Thursday you would just use (due:Tomorrow) but to keep weekend tasks from displaying on Friday and Saturday you need to add (AND dueBefore:Saturday)

which gives us:
(due:Tomorrow AND dueBefore:Saturday)

To show Mondays tasks over the weekend we use (due:Monday) and restrict it to (AND dueWithin:"4 days") so we don't see Monday's tasks during the rest of the week.

this gives us:
(due:Monday AND dueWithin:"4 Days")

Show the results of either of these searches and you will get the tasks due on the next weekday:

(due:Tomorrow AND dueBefore:Saturday) OR (due:Monday AND dueWithin:"4 Days")

Correction.

Using dueBefore:Saturday will cause Sunday's tasks to be displayed on Saturday. To fix this issue use NOT (due:Saturday OR due:Sunday) instead.

Corrected search:
(due:tomorrow AND NOT (due:Saturday OR due:Sunday)) OR (due:Monday AND dueWithin:"4 Days")

Terrific, thanks for the quick replies !

Forgot to add one thing. I'm trying to create a smart list that will always inherit a due date of the following workday. As such, I don't think this will work, since it uses "OR".

Any other thoughts ?

No, there'd be no way to use the "inheritance" feature within this kind of search; you could use due:tomorrow but, of course, that would include weekends.

Bummer, but thanks for the reply. Is there a way to request a new feature ?

Consider it requested. ;)

@steveshay - Terrific, thank you.

That's terrific, looking forward to the feature !