When it comes to optimizing spring attack, there are a few ways to do it. First there's getting a use out of your move action, such as improved feint comboed with sneak attack or some other high damage. The next is going all in on two weapon fighting and picking up 5 levels of tempest and the bounding assault feat from PHBII (rapid blitz is nice, but 3rd attacks are generally not going to hit except on or near a 20.) Or you could do both, just at a later level. As was mentioned, snap kick is also an option. Especially if you focus on beefing up your damage rather than the number of attacks.

Spring attack is usually relegated to being "bad" simply because there are so many ways to buff charging. Unlike charging however, spring attack can't be shut down by terrain, obstacles, set weapons, side stepping, etc. I like to look at spring attack as an enabler. It enables you to get into flanking positions you wouldn't normally be able to reach without or much less risk and at full speed (tumble has you move at half speed).

An interesting interpretation of the weapon master (kensei) PRC is that Ki Whirlwind Attack could be used with spring attack. Spring attack requires the attack action and whirlwind attack requires the full attack action. As the ability only makes reference to WWA as a full-round action, then for consistency when it references making it as a standard action you can use it as an attack action. This understanding only works because WWA is not a special full-round action. The full-round attack action is the full attack. The standard action attack action is the attack action. As with anything PRC related though, just talk with your DM. Anyone disallowing it is arguing more about RAW than any power imbalances it could cause.