This route offers access to ascend both Mt. Shasta proper and Shastina.
The route follows the obvious gulch leading from the upper left of Hidden Valley rising to the saddle that splits Shasta from Shastina. The time of year/snow pack will determine the best line up through Cascade Gulch to the S/S saddle. A bivouac here could be an ambitious proposition when the reality of winds and fatigue are considered. A bivy below the saddle is perhaps a better option.
If Shastina is your objective a left turn at the pass and a short climb lead to the summit cone that tops out at 12,330 feet. If the Mt. Shasta summit is your goal you have some options from here at the S/S saddle. One can either traverse onto the Whitney Glacier (a rope and glacier travel experience is recommended), climb/scramble the ridge line above the glaciers, or traverse onto the West Face.
Seasonal variations and your experience level will determine which route is best for your party. You could easily burn up three days enjoying this part of the mountain.
Cascade Gulch is in good shape. This route is listed in many books as "easy", though it can host patches of ice and some exposure to glaciated terrain, crevasses, and bergshrunds where it crosses the upper Whitney Glacier. This hazardous stretch is a minimum of 1/4 mile in length. Glacier travel training is recommended. One can ascend climbers right onto the West Face ridge from the top of Cascade Gulch, though you will find sections of loose rock and tallus and perhaps even some 4th class scrambling if you stick to the ridge proper. This route overall is very "roundabout" but hosts beautiful views of the Whitney Glacier, the east side of Shastina, and is an area of the mountain not often traveled. Camping in the saddle of Shastina and Shasta is awesome, but be prepared for nuclear winds. Melt snow for water currently and anchor your tent well in Hidden Valley.