selectedItemText should give you the value of the selected item in the combobox
The problem in many cases is, that before the selection becomes active the "popup" with the elements is closed and the selection, or click has no effect,
so I implement something like
ListItem item = comboBox.ListItems.Where(p=>p.Name=="name").First();
item.Click(); or item.Select();
in some cases I build a little loop that check the selectedItemText and try again if not correct.
it might be that the method comboBox.Select("name") works not as expected, maybe it's a performance problem on fast machines or to slow machines, I don't know.