I would first just start with better pads (Hawks) and see if that does what you are looking for in terms of stopping power. You'll feel a massive difference without having to buy new rotors and calipers. Start there and then decide if you really need bigger rotors. Stainless steel lines are a good upgrade. They won't fade from heat expansion and you'll have less pedal travel which improves feel and confidence. Plus they'll last pretty much forever.
OGOC (Ontario G8 Owners Club)
09 PBM V6 (Traded)
GXP Diffuser, Mace Insulators, Solo, CAI, FE3, BMR, much more
09 WH GT, Solo Mach, HF Cats, CAI, LS3 Cam, Pat G Tuned, FE3, Whiteline, SuperPro, Centric/Hawk, DAI Autobahns 19x8.5/+35, RE760s