what do i need to check on a 2007 grand prix for a long trip?

Take a good look at your tires, decent tread, look for wear indicator on tire, or use the old penny trick. Put a penny in the tread Lincoln's head in and if you can see the top of Lincoln's head the tread is not deep enough. make sure spare is OK even if it's a donut, change oil if it is due or near due... check transmission fluid...inspect your serpentine belt, no fraying on edges or cracks (replace before travel if you see anything like that). No corrosion on battery terminals, Coolant good, you should be ready to hit the road. be safe and happy traveling!