How about making those work differently based on your base save?
My idea is:
if you have good progression, +2 (as before).
if you have low progression, you then get good progression.
This way, PCs with low progression get more out of it, but PCs with good progression still achieve an higher bonus to the save. No differences for the improved versions.
How does that sound, is it really too strong? Would it become a feat tax?
What about multiclassed PCs? My idea would be to give the best between the +2 or good progression as more advantageous to the PC at every level (kind of like toughness)
if you have low progression, you then get good progression.
Imho that's too powerful.
But I remember feats from somewhere that allowed you to replace one attribute with another for bonuses:Fortitude: usually con, then became str
Reflex: usually dex, then became int
Will: usually wis, then became cha
In 4th ed. they automated it, which is bad, imho. But I guess spending a feat to apply charisma instead of wis to will saves should be ok for a sorcerer?
If you want to boost saves I'd consider making saves 1/2 character level, instead of good saves you can build a bonus to saves inherent in the class, perhaps as a bonus feat at 3rd level or a gradual increase in saves like the bravery class feature. It makes saves dependant on ability scores foremost and has no weak saves in and of itself.
As a side effect saves are extremely easy to calculate and invites less metagaming or extremely high/low saves for multi-classing.
Clerics could get a class feature much like bravery giving a bonus on saves vs energy drain, poison and death magic.
Wizards possibly a bonus on saves vs spells.
Rogues get 'Danger sense' a more general bonus on reflex saves and dodge bonus to AC vs traps.
Fighters have bravery replaced by 'fighting spirit' allowing reroll on any fortitude or fear save.
I am sure something can be added or expanded upon within every class to affect saves in a fitting way.
I would love some mechanic like "roll twice and take the higher result". even a "you can reroll but must take the second result, even if it is lower" would be more fun in game than a boring static bonus.
I thought about those feats too.
I think they should simply give +3 instead of +2.
This would bring a bad save up to "medium" and "medium" up to good.
So maybe those feats should be able to be taken twice.
OR:
IMPROVED RESISTANCE
Benefit: Choose one saving throw type (Fort, Ref, Will).
You receive a +3 "???" bonus to this saving throw.
In addition, once per day you may reroll one saving throw of the chosen type and keep the second result.
Special: You can take this feat multiple times. Once for every saving throw type.
GREATER RESISTANCE
Prerequisite: Improved Resistance.
Benefit: Choose one saving throw type (Fort, Ref, Will) for which you possess the improved resistance feat.
You receive an additional +3 "???" bonus to this saving throw.
When you use the improved resistance feat to reroll a save, you may keep the better result instead.
Special: You can take this feat multiple times. Once for every saving throw type.
Never thought about doing this-- I always just combined the saving throw feats with other feats.
Great Fortitude includes Endurance.
Lightning Reflexes includes Improved Initiative.
Iron Will... I never could figure that one out.