Not in the market for optimization here, since we accidentally overoptimized for one campaign and mashed its face in for the entire latter half. This means remain effective, but there's no need for starting stats of 20 or perfect feat selection.
We're only allowed to use core races and classes, but spells/feats/archetypes are allowed from any of the books.
Next campaign I'm going to play a Wizard, and have been considering taking a touch/ray spell subfocus to the character. If I do so, are the two CL lost from going into EK painful? Am I better off taking 1 level of Fighter and not bothering with EK? Or just having a decent-stats pure Wizard with proper feat selection?
And speaking of CL lost, is Magical Knack the only way to get any back?
Eldritch knight is still a very good prestige class-- I think it's one of the strongest ones, actually. The only beef I have with prestige classes is the loss of favored class bonuses.
For PFS, I think that Magical Knack is the only way to boost caster level.
In my home game, I allow the 3.5 feat Practiced Spellcaster (from Complete Arcane). That feat grants a +4 bonus to caster level for 1 spellcasting class (up to a max caster level of character level), although the character prepares a number of spells equal to actual level.
e.g. A wizard 3/rogue 3/ arcane trickster 3 normally casts spells as a 6th level wizard. With Practiced Spellcaster, she would prepare a number of spells as a 6th-level wizard, but casts them as if 9th level.
This, of course, requires your GM approval, and uses WotC intellectual property. But it works quite well in my home game.