I understand the problem you are having...
I do two things here. First is adjust the DC for the distance to the caster from the identifier.
I use the Close, Medium, and Long ranges as the standard... (Close is 25' + 5'/2 lvls., etc.) I use the identifier's caster level for the distance. If the identifier is within close to the caster of the spell, then the roll is normal. If it is in Medium range, then I add +2 to the check. If it is in Long, it is too far to see and hear what is required to identify the spell.
The second aspect is when dealing with types of magic. If there is a difference between Arcane or Divine (or Psionic), I add +5 to the roll. If the identifier is using the same type of magic, but is from a different class, I use a +2. I only use the higher of the two.
Two examples using both systems:
1) A Wizard casts Ice Storm on a 10th level Sorcerer who wants to identify the spell at a range of 50' from the Wizard. The normal DC for this is 19, (15 + 4). Because Close range for the Sorcerer is 50', then this spell is Close, no addition. Because the identifier uses the same type of magic, Arcane, but is of a different class, the DC increases by +2. My new DC for identifying the spell as it is being cast is a 21.
2) A Cleric casts Firestorm on a party with a 18th level Wizard at a distance of 200'. The Wizard is galled at the fact that Clerics have so much offensive power! What is that spell? The Wizards close range is a maximum of 70'. His Medium is 280'. He can still see what is happening at 200' but it is hard to make out.... a +2 for the range. Also this spell is a different type of magic, Divine, and something he isn't too familiar with; a +5. The DC moves from the normal 23, to a modified DC of 30!
If you find that certain spells are just too personalized or exotic, then just add another +2 to the check!
Of course, this is my personal system..... not the system as written.
Aluvial
EDIT: You know I was thinking about this... in most of my campaigns, the PC's tend to Max out Concentration and Spellcraft.... in the first example, the Sorcerer would likely have a Spellcraft of at least 13, modified by his Int. With the DC at 21 the Sorcerer has a 60% (or better with any Int modifier) of identifying the spell. Not bad...
In the second example the Wizard likely has a Spellcraft of 21 or higher... just figure that an 18th level Wizard is at least going to have a 18 Intelligence at this point, which is probably underestimating items and buff spells, they would have a Spellcraft of 25... The Wizard has at least a 75% chance of successfully identifying the strange, high-level magic of the Cleric!
Aluvial