I think what needs to be done is that there be some flavor summons that are balanced/made useful for each level and maybe creating a difference in summons between a wizard/sorc/bard, cleric, and ranger/druid.
IE: Wizard/Sorc/Bard would summon magical creatures from like Tressyms, goblins, and all the way to Unicorns lawl
Clerics: Similar with above, but maybe alignment based, or just make them like the above.
Druids/Rangers: Summon powerful and mortal creatures.
I'd also like to see the Planar Binding spells, as well as Ally, when used, for them to be Representative of alignment, as well as after the spell is over having the monsters become hostile or at least annoying as if you gate beings in from outside the plane, or even within, they don't go away they are stuck here and now have a phylactery. So if you summon a Pitfiend, it is going to kill you after the summon is up because you just ruined his day. lawl