Rolling everything. Either bards and rogues are totally useless (or wind up just being tricks to twink damage out of less obvious combat classes), because you just roleplay everything social, or else, everything goes "I ask about the plot. I have +12 Gather Information. I rolled a 17. That's a 29." This actually goes for EVERYTHING in the game - acrobatics, armor, ancient lore, etc. Nothing is left to the imagination. Other games, it's simple. There's an acrobatics skill and some general guidelines for difficulties. NO! In d20v3.5 everything has to be spelled out for you in hyperrational terms. There's 963 words for the goddamn JUMP skill! Why do you need 431 words for Use Rope??? It takes 100 words and potentially 2 die rolls just to secure a grappling hook! The system is so well balanced it hurts (it reminds me of balancing a broom on your palm - you're constantly adjusting and you can't ignore it or else the balance goes, and you get hit in the head).
Combat is similarly lame. Nothing dramatic happens because everything dramatic has become a system of AC/DC. There's so much rolling and book-consulting that it discourages anything but "hit with sword, fireball, hit with sword."
Magic items are also pretty disenchanted. Imagine a 20th level fighter with ONE magic weapon - say, a flaming magic sword. That leaves him with 21 or 22 AC - not that impressive, and even a party of 4 of him is not capable of standing up to any CR20 monster. You need two rings, an amulet, a cloak, a shield, armor, sword, bracers or gloves, boots, a belt, potions and other miscellaneous things as well. It's an assumption of the system. So things like a Ring of Protection are so un-wonderous they're hardly "wonderous items." It makes me feel like I'm playing pen and paper Diablo.
I'm running d20v3.5 right now (yes, the name even sounds hyper-rational), and I'm really having a hard time with it. The mechanics, which I admit, are very well balanced in any respect I could wish, and then some, iust won't stay down. If you play fast and loose, players always run away with system (if you know your chaos theory, d20 makes me think of the principle that higher complexity increases the liklihood of random catastrophe). Besides, you can't play fast and loose anymore. The Spider Climb spell gives you +X to climb, where X is variable depending on caster level, for instance, and that's typical of the spells.
To pre-empt the obvious answer: No, I don't want to use a different system. There're 7 of us - 2 college students, 1 grad student, 2 people between jobs, and 2 gainfully employed. I can't ask the whole crew to go out and buy/learn a new system. Plus, I want to know how to run D&D right. I used to do it in 2nd edition, no sweat, but then there weren't so many
So what can I do to put the fantasy back into this bored game?