If the House of Representatives remains in GOP hands, and ends up more conservative than the Senate anyway, then what difference does it make who controls the U.S. Senate? The Republican Senate leadership hasn't even laid out a plan for what they intend to accomplish if they are the majority. That right there tells me everything I need to know.
The Senate must approve all Obama political appointments. There is a significant likelihood that at least ultra liberal Ginsberg may not make it through the next two years. A Republican Senate could block an ultra liberal replacement. A Senate controlled by Harry Reid would approve one. There are a multitude of other appointments to be blocked, as well.