So, one of my greatest points of contention with the d20 system - and unfortunately, it is something that translated over to the Pathfinder rules set - was how static combat is. Any standard encounter becomes a fixed point - creatures find their optimal positions, and then sit there for minutes at a time trading swipes until they die, are driven off, or come out victorious.
This isn't just an issue of the resolution becoming boring, either; characters that are built around multiple attacks a round (*coughmostmartialscough*) get absolutely screwed anytime they have to take more than a 5 foot step to get to their enemy. It's even worse when the enemy can teleport or move the PC's around the map against their will.
But a real fight doesn't flow like that. You don't stand stock still in a single 5 foot area trading blows with the same person for 30 seconds. You duck and you weave, you jump around, and you run the fuck away to get a better position when you can't get past their defenses.
To address this, I'm going to start instituting a house rule that alters the way full attacks perform. The Full Attack action remains in the system, but completely re-written.
When you take a full attack action, you can move up to your current modified speed as with a normal move action, and can split that movement up before and after each attack. However, every attack that you make after the first consumes 5 feet of your speed - that is to say, if you stepped 10 feet forward and made two attacks against an enemy, you just spent 15 feet of your speed for that round. Your total effective movement for the round cannot exceed your speed, so if you run out of movement but still have attacks left you lose those attacks for the round. Extra attacks you gain from magical sources, such as a Haste spell or the Speed ability only consume movement if they miss.
Anyone who has played the 5th edition rules set for Dungeons and Dragons may recognize this "some actions consume movement" mechanic. I feel like this is an absolutely brilliant way of balancing what a character can do in an encounter with what the group of players imagines when they think of fantasy combat and what any individual player wants to be able to do in order to have fun.
This changes the way the Spring Attack feat functions, as well. With that feat, your total effective movement that you can perform as a Full Attack becomes twice your speed - but only for the purposes of making extra attacks. You cannot actually move more than your speed in a round, and any left-over "extra" movement doesn't transfer between rounds but is lost. This also does not allow you to perform additional attacks beyond what you are actually due simply by virtue of having any of this extra movement left over.
This is the best way I have come to balance my ideas with how combat should run, with fairness in the game mechanics and - more importantly - the fun of my players. A character with multiple attacks per round but WITHOUT Spring Attack can still benefit from them even if they have to get up to an enemy, though to a more or less limited extent which prevents the mechanic from being abused. And then those with Spring Attack have spent a whole feat in order to improve on this, and even then still are limited to the number of attacks they could make anyway. They just get to actually *use* them without having to bore themselves and the rest of the table to tears when we're all imagining the leaping, running, and plain-old *fluid* combat of fantasy media.