SATs are far more important than GPA for admission. A GPA over 3, as another poster noted, will get you a hefty Good Student Discount on your car insurance. Class Rank in the Top 5-10-15% might get you some grant money for an in-state school.
Depending on your major, the CC to 4-year school plan will save you lots of money. An exception in many cases is Engineering, since the 4-year curriculum is pretty well set and general studies are credited into the engineering curriculum.