1-New Tower. Add multiple levels of indoor/outdoor club level seating. And add as many luxury boxes as possible by extending the tower all the way to the North & South corners, not restricting to to just behind the west stands. Also add reception space for improved recruiting, Cougar Club, and event & revenue, etc. This is the best ROI of any potential stadium project. And finally, give it some architectural appeal to give the stadium some character. And frankly, if the tower looks good it isn't really necessary to wrap the rest of the stadium. The current press box is a complete eyesore from outside the stadium.
2-Fill in the corners below the concourse and complete the lower bowl. Even if this is done just to accommodate table seating like they did in Sec 33, the stadium will look complete and the ROI will be there because there is always demand for more seating close to the field. Filling in the corners in the upper bowl would add too many seats with minimal value.
3-Turn Section 133, 134 & 135 into chairback seating. Even though those seats are in the upper bowl they are still in prime locations and could command top value, just like the midfield upper bowl seats on the West sideline. But keep the seats around the endzones bleachers to continue offering affordable options to families and for the noise.
4-If the stadium ever needs significant expansion add a 2nd deck on the East side. But do it in a way that preserves the view of the mountains. Most likely this would require it to significantly over hang the existing upper bowl without impacting sightlines.