Optimal form of pointer/scrolling integration for portable keyboards?

I'm considering my next keyboard purchase to include a solution that would preclude the need to keep an external mouse/trackpad with me. But i'm curious how well integrated trackpads, pointers, etc actually work as a complete solution, particularly for more portable keyboards. For example, do people actually like using a circle trackpad? Or do you gravitate back towards a dedicated mouse? If so, why?