Alright, I've gotta say I disagree here- I love options.
However, I do have some pet peeves...
1) Use options that fit the setting. If I'm running a campaign that has a Tolkienesque or Arthurian flavor (like my current campaign based off the R&R: Excalibur book), I don't want to see psionics, katanas, asian-style martial arts, mind flayers, gnolls, good-aligned goblinoids, tattoo mages, fleshcrafters, steampunk-style "tinkers", firearms, samurai, extraplanar travel, shugenjas, etc... all of that spoils the flavor of the setting. On the other hand, here are a few things I would allow:
Some of FFG's legendary classes- the Black Knight, Jack O' the Green, Oracle, or Wizard King.
Many prestige classes from other sourcebooks- Bladesingers, Crusaders, Cavaliers, Knight-Hospitaler, Seeker of the Misty Isle, Thief-Acrobat, Clan Champion, Brother of the Cloak, Song Mage, Mirror Master- all of these fit the flavor of the setting.
A few races: Half-Fey, perhaps. Maybe Tieflings. The Faen from Arcana Unearthed.
A few base classes: Commanders, Nobles, Witches, Monte's alternate Bard, Akashiks (as Fae loremasters), Magisters, Runethanes, Delvers, and Greenbonds all fit the setting well.
Most any feat is all right, as long as it's not broken (spellfire, a few third-party combat feats) or based on a setting-inappropriate concept (psionics, asian martial arts).
That's only a sampling of what I'd permit- but it's flavor issue more than anything else. The other day a player said that he wanted to go for the "Weapon Master" prestige class- I ruled no. It's based on Ki, a concept that doesn't exist in my setting. End of discussion. In my collection, there are at least 100 prestige classes that I'd permit- one of them should fit your character concept, if you feel you need one.
2) "Cantina-scene parties"
For my latest campaign, I told everyone that the races in R&R: Excalibur were the only ones permitted. However, if someone now asked me if they could play a non-standard race, I'd probably permit it.
Why this policy?
Have you ever tried making adventures for a Kitairn (a cat-like humanoid from AEG's Mercenaries), a Kobold, a Half-Orc, a Human Lich, and a Half-Celestial, all of greatly differing alignments? I have. I found it next to impossible. The campaign barely lasted a session.
On the other hand, if you have a solid party of common races (the current party consists of three humans and four elves), and someone decides they want to bring in a non-standard character, it's much easier. You already have a party of characters established in the mainstream of your campaign setting, and some semblence of a plot that the new character can be worked into. At this point, it adds some flavor to the party.
3) My take on game balance.
I've known GM's who frequently complained that leadership was an unbalanced feat, or that granting cohorts made adventures too easy. There's a simple solution to this- more enemies, and harder enemies. Your players made characters a bit more powerful than the norm? Give them similiarly scaled opponents. In 3e, unlike 2nd edition, it's easy to ratchet up the power of your encounters by slapping hit dice and class levels on your monsters. Use this to your advantage, DM's! All too often every monster I encounter in an adventure is at base HD, when it might have an advancement limit far beyond that base. And, all too often my players have assumed that the party of hobgoblins they encountered were first level warriors, only to discover, much to their chagrin, that they were 5th level fighter/barbarians... ouch.