I would definately just spend the nite, the day trip is just too short to get the feel for C.C.
Staying overnite you can spend about a day & a half if you want.
the round trip water taxi is still good the next day or whenever.
Even though we had our room in S.P. It was so cheap in C.C. it really did'nt matter.
9 mo sleeps & I'm there!! YEE HA!!