Honestly, I'd love an extension from Vaughan Metropolitan to Vaughan Mills. Would def reduce the amount people who drive to the mall. Maybe we could have an extension to Wonderland?
Wonderland would perform well in the summer, but very poorly off-season; however, the north end of Wonderland is directly opposite a brand new, large hospital and healthcare campus which employs a large number of people (1,800 full-time staff)
The case could certainly be made for a station with the north end having an entrance on the north side of Major Mac, serving the hospital, and one off the extreme south side close to the existing principle entrance to CW.
That would place the south end of the platform ~500M from the main entrance to Wonderland. A bit closer would be ideal, but 2 stations here would very hard to justify and the hospital should be favoured.
Vaughan Mills generates a fair bit of traffic and would 2.1km south of a Major Mac Station (I'm placing it, in theory on the south side of the Jane/Rutherford intersection based on the Mall being the only significant draw in the area currently. Langstaff would then be another 1.85km south, followed by the existing VMC station ~2km south of that.
So 4 logical stations evenly spaced.
You could argue for omitting Langstaff in the midst of low density employment lands; but I think the 4km gap that would leave is excessive, I would just minimize the scale of the station to save costs if possible.