Considering how often the following has come up, I'd like to suggest something completely different.
Baby Samurai said:
I would actually like a system where characters and monsters get their full array of attacks as a standard action, thus giving combat more movement and moving away from standing in one place and hacking, which becomes even more apparent at higher levels (for melee types). At levels 1 to 5 a fighter can move and still get his full attack, but suddenly when he reaches 6th (1st iterative) he's encouraged to not move more than 5 ft. a round and stand there like a schmoe – we must fix this.
Keep iterative attacks. (Yes, I know this is a thread about eliminating them, but aside from the above objection -to which I will propose a solution- the only real criticism I've heard of iterative attacks is that it means more dice rolling. Unless I missed something. Still with my suggestion you could still reduce roles using the AD&D attack varaint ie. BAB 1-5 1attack, BAB 6-10 1 1/2attack, BAB 11-15 2attacks etc.)
Keeping Warriors mobile Variant
I see two possibilities,
1) Warriors Classes (and most monsters) can full attack throughout their move action. They can attack any enemy they can reach in a move action.
2) Warriors Classes (and most monsters) can full attack throughout their move action as long as they only move half of their Base Land speed. They can attack any enemy they can reach in half their move.
This would allow for some serious tactical movement on the part of the warriors. I believe it would help to remedy some of the classic feeling that spellcasters outstrip warriors at higher levels.This would make some feats redundant for warriors under 1) and subpar under 2) : mobility, whirlwind attack (any warrior can now attack whomever he please with his 1st 2nd third and fourth attack), ride-by attack. This would also increase the abilities of TWF. (Although I suppose it would also really helps those with Cleave because of your ability to move between attacks. You'd probably have to limit Great Cleave, say to a number of attacks equal to the characters Str Bonus.)
Moreover if you adopt the all Warrior types are mobile there is much less alterations needed to the rules, characters and monsters. Most monsters should also gain this mobility -- all the monsters that are focus on dealing non "magical" damage. It's a lot less work.
I also believe it is much less potential to be unbalancing as some of the ways of eliminating iterative attacks.
It does make monks much stronger because of their many attacks and because of their increasing base land speed. Helps Barbarians as well for the later reason and hinders warrior classes with 20ft movement (dwarves, gnome, halfling). Could be good could be bad.
Of course if you don't feel that Warrior types need a boost then you could let all classes gain this mobility. Perhaps the better solution is to let Bards and Rogues gain the mobility (after all Iconicly they are the ones ducking and weaving through combat) and restrict only the spellcasters to only being able to move 5ft and full attack.
Anyway, in some ways that was completely changing the topic.