You won't need lights if it's 70 and sunny. You'll need 2 water bottles. You may want a drink with electrolytes in one of the bottles.
I wouldn't bring a pannier (I'm not saying you shouldn't, just that I wouldn't ). My flat kit fits in my saddle bag, and my snacks go in my jersey pockets. I travel light. If I knew there were stores that I had to buy something in in order to use the bathroom, I might not even bring much to eat, maybe just a bar or some dried fruit. The only other things I always ride with are my cell phone, id, and a credit or debit card.
You're going to have a great time!
'02 Eddy Merckx Fuga, Selle An Atomica
'85 Eddy Merckx Professional, Selle An Atomica
'10 Soma Double Cross DC, Selle An Atomica
Slacker on wheels.