Yeah, really, for archivists you've got plenty and plenty spells to choose from. If you don't have a spell compendium yet, get one. Read over all the domain listings and stuff, and make a "to-do" list.
There's also a rule loophole in the Archivist: there's an argument to be made that prayerbooks don't cost 100gp a page to fill in the way spellbooks do. The rules in HoH only reference part of the rules (those for the spellcraft check) but don't mention an ink cost. It's debatable, and I bet the spirit is to make it cost 100gp per page, but as RAW goes, it doesn't.
Finally, I prefer just looking toward Sacred Exorcist if you're looking to cheese out persist. A level of cloistered cleric, however, gives you a LOT, and you can't go wrong with CC1/Archivist 19. There's way more things to do than feats to support, so you can really do a lot of different things with archivist. Which is precisely why I like them.
The main break point for archivist is level 11, I think. Whenever you get Dread Secret. That's huge.
Oh, also, get a copy of Complete Champion. The Knowledge Devotion feat is really neat for archervists, and Lore of The Gods is a 2nd level spell, 10 min/CL, +10 on knowledge checks (!).