High levels
Things picked up from around level 11 to 14. Enemies started getting more interesting, they started to fly, or turn invisible or incorporeal. Hitpoints started to shoot up at this level, I don't know if it was the modules or the DM giving his bad guys more longevity.
Once you get past level 10 then the average fighter needs casters to function at all, casters are alternatively even more powerful with their ability to screw over the opposition with just one spell. That said some enemies just have really high saves, beatsticks can still have a place in the party if they can stab faces even harder than before. Tome of Battle classes are a nice middle ground, still capable of high HP damage but being much more adaptable.
The final module saw my first attempt at Scry & Die. I was actually pleasantly surprised that they made the final boss's lair protected by mage's private sanctum. His lair was actually a dungeon we cleared between level 4-6. The designers where not so clever as to stop Contact other Plane from giving us his location to within three rooms. Since we didn't have the exact location, we made the Swordsage silent and invisible. The BBeG actually had a perception check high enough to hear
a silenced person sneaking, which was a funny surprise.
Lessons learned:
Scry and die. It works, but it's easy to guard against, I guess.
Contact other plane. This is a dangerous spell. Not just for your enemies, it's quite possible to loss Int/Cha during the middle levels so take every precaution you can. Also be careful of lying responses.
Get a Really high perception check. I'm not sure how to get it high enough to deal with invisibility, but it would be nice to have.
Craft Contingent spell. Really expensive when you first get it. To put a Revivify and a Heal on yourself it costs about 6K of a WBL 66K. The security is nice but I've got to wonder if the money couldn't be better spent.
Cleric spell list. Really boring at lower levels. While a Wizard is shooting lasers out his eyes your giving yourself +3 on all saves. Debatable which is better, one definitely has the better visuals though. It gets better when you start getting 3rd-4th level spells. I mention it now because no one ever seems to bring it up.
Figthers with potions. I've never seen a fighter played intelligently with respect to magic items. Think about it, your charging shock trooper friend could be starting the next encounter invisible if he is willing to use a potion. Conversely every fighter should have at least a potion of see invisibility on them, but they never seem to. Which leads me to:
Buff your beatstick. Because he won't do it himself.
You only have to out-optimize the DM/adventure. Our DM prefered fighters, so most of the encounters with spellcasters we got where unedited. Which meant they where a cake walk. So while I could have take a GOD/Incantrix build, even a Warblade or possibly a Barbarian could have done just as well.
Questions left unaswered.
Pathfinder CMB system : Weal or Woe? It's a lot easier to use, so at points where a direct approach wasn't working we'd try sunders, disarms or trips where before we just would have attacked again. I haven't seen any builds yet based on exploiting it in play.
Pathfinder Spell nerfage. I'm paranoid, I really wish that contact other plane had been toned down because I can't defend against it. Pathfinder did nerf a bunch of previously 'I win' spells like Solid Fog and Glitterdust. It's annoying when your side can outcast the other's but it throws a bone to Fighters everywhere. Lets be honest, not everyplay is cut out to play a caster.
Is it better to buff the beatstick or do it yourself? Say you have a 5th level slot, what's the best way to use it? You could debuff/BC and win a fight, but a good fighter buff could win a few fights if go through the dungeon swat style.