I'd consider adding if for no other reason than to add some variety to a 'generic' list that could then be rapidly narrowed down. Start with 8 and cross 4 off, for example, for a more rapidly generated and varied list or to generate a list for a more specific function(ary):
Cantrip
- Arcane Mark, useful for making many other utility spells either work or work better (Locate Object, Scry or Instant Summons as examples).
- Mending, useful after your cup of coffee or 'pet' damages your last couple hours work. Mostly redundant if you also have Make Whole but endless supply owing to it being a cantrip.
- Message, for when you are tired of yelling out to the next room full of scribes (or courtiers) that you want to talk to "Bob" Also works 'through' several scrying type spells.
First
- Peacebond, not CRB but ... lots of potential flavor. "No one gets within 30 feet of Her Majesty without one!" (Concept screams for a higher level version able to 'peacebond' your average higher level group with one casting - one weapon per level or creature per level)
- Unseen Servant, many obvious step and fetch uses.
- Shield, if there are commonly lists with "Magic Missile" stands to reason they'll be 'lists' with a spell designed to block it.
- Detect Secret Doors, again role oriented. Is this a 'detective' or 'bodyguard' npc, for instance.
- Floating Disc, hauling whatever around for whatever engineering project.
Second
- Knock, if there's folks using Arcane Lock they'll be folks using Knock to bypass it. So does the characters role make him the Warder or the one getting around the Wards?
- See Invisibility, particularly if they haven't got Permanency to make this available all the time.
Third
Starting to really get lots of options depending on the role or function the npc caster actually fulfills within the campaign.
- Nondetection, especially effective if you are one of the higher level wizards around (i.e. the old retired adventure type)
- Phantom Steed, need to get somewhere fast but for whatever reason Teleport isn't available or doesn't work. Except in very mountainous terrain it's likely much faster than Overland Flight and, of course, not a personal spell either.
- Clairaudience/Clairvoyance, potential use as rapid communication if both ends are known points and can use the spell.
- Illusory Script, should be on any spies list.
- Secret Page, much like Illusory Script.
Fourth
- Scry, there's a reason there's Detect Scrying.
Fifth
Mage's Private Sanctum, on your list but thought I'd point out the synergy and usefulness of Secure Shelter+Mage's Private Sanctum for an on the go anywhere you currently are and need a secure meeting space.
- Telepathic Bond, particularly if the Permanent version with another individual or two is employed. Pretty near the ultimate, on the same plane, communication spell.
- False Vision, a potent mess with any potential scryer information gathering. Few things are worse the no information, one of them is disinformation.
- Seeming, more or less a communal version of Disguise Self with a 12 hour duration. "No, no sir I didn't see any such group of elves pass here recently."
- Overland Flight, does the npc regularly need to travel or just need to get at the top shelf in the scriptorium?
- Permanency, so many utilitarian spells can be made permanent and hence not need memorizing any more including several spells previously listed. Doesn't necessarily need to be on the memorized list but occasionally assuming a slot was or is in use for Permanency might be a good idea.
Sixth
- Repulsion, particularly if it is one caster vs many lesser level/HD foes (and presumed low, relative to the DC, Will saves), doubly so if not wishing to inflict harm on said foes (like an angry mob commoners).
- Analyze Dweomer, another potent divination spell.
- Contingency, much like Permanency mentioned more to remind one to occasionally leave a slot open to account for its usage as most higher level arcane casters (particularly any retired "adventurer" types) will access this spell.
- Quest/Geas, Isn't this what high level casters do to us not so retired adventurer types? :p
- Veil, now the composition of the group of can whatever they want.
Seventh
- Sequester, need to hide something this is the spell to be using. Probably needs a FAQ (and or errata) but it's quite possible to interpret that even Discern Location doesn't beat this spell as the wordings of both spells tend to defeat the other. But most of the things our retired wizard is trying to hide probably don't routinely have Discern Location being used against it either (and likewise it's probably overkill to use Sequester to hide it but ...).
- Instant Summons, need something you generally don't want to keep on hand but might want it NOW this is the spell to use.
- Phase Door, can be made permanent.
- Limited Wish, I wouldn't be without this one (or at least access to it when desired). Any 4th level or lower spell regardless of class, school, prohibitions etc. is yours to duplicate and potentially upwards to 6th level spells. Tack on what's allowed by the last two bullet points in the spell description and you have one very versatile (albeit expensive) spell.
Eighth
- Mind Blank
- Protection from Spells, often of limited value to adventurer types who have access to lots of items and abilities. But how about a much more mundane, but similarly small group of wards. A boost across the board of +8 resistance vs spells/SLA'a to such a group might be irreplaceable.
- Moment of Prescience, really need to make that Sense Motive check vs the Drow Ambassador or a save or ...
- Demand, Sending with built in Suggestion.
- Screen, like False Vision only now you can add in direction observation to those receiving disinformation.
Ninth
Thinking about things other than Wish and perhaps less adventurer and more 'patron' oriented.
- Refuge, want the King, or whoever, to be able to call on you even when you aren't at hand and possible a great distance away?
- Foresight, think about the combined effects of Foresight used on your "ward" and a permanent Telepathic Bond. Other than being on the same plane of existence (for the Bond) nothing says you need to be close by to give warning. Or Foresight (on the ward) and a previously cast Refuge +/- Telepathic Bond
