Line Paths Alternative? Is there an easier to work with way of moving an object around a scene than with line paths or normal keyframes?

I’ve been having lots of trouble with line paths as I can’t figure out how to make objects continue on doing other animation once they’ve completed the line paths.

Also regular keyframes are hard to nail the proper speed and is also difficult making a curved turn.

Any suggestions?
Instead of parenting your object to the path, you can use a "follow path" constraint. 

Set the offset value to the frame number you want your object to follow the path and in the same frame set a keyframe to put the object in the 0,0,0 location. Push the button animate path in the constraint tab, and set the timing of the path in the curve's property panel, "path animation" tab. 

A the end of the animation set some keyframes to animate the influence of the follow path constraint, so you will be able to freely animate your object.