You really could roof the first option if you prefer the style over the second option. It would be as easy as just applying a grade % to one side to allow for runoff. Good luck with everything.
I honestly think you'll live in hateful regret if you do not put a roof on it. The PVC panels mentioned above are not expensive at all for the clear ones, 4 x 8 I believe at about $14.00 a piece. Well, if that's pricey than prepare yourself for the chicken hobby..it doesn't stop costing money...