It is swimming weather!!!
As far as hopping, I personally would hop back and forth on both days. It's super easy, it's really not like changing parks, it's more like walking a little further to the next rides!! And this way you don't BURN precious hours waiting for CA to open and instead of wasting the time after CA closes, you hop back to DL.
IF you really do not want to hop, my choice would be Saturday at CA and Sunday at DL. But since hopping is so easy there, I don't know why anyone wouldn't!!! (Unless you absolutely could not get a hopper ticket, or had 2 free 1 day tickets) It would have to be a weird circumstance to make me not go to both in the same day!
Andrea