For hotel guests, Valet charges are typically attached to the room on a nightly basis. They aren't on a 24-hour schedule. So, if you arrive at 11am, it should only be $25 even if you get your car the following day any time after 11am (but before the hotel system changes the day).
If you do decided to pay for one night of Valet service, I'd recommend two things. First, ask your question when you arrive. The Valet attendant will provide the most accurate information regarding the time period when a second charge happens. Second, be sure to let the Valet and/or Front Desk when you pick up your car that you don't need valet parking for additional nights. Otherwise, they may assume you want it throughout your stay.
That said, I do think that fairygagamother gives good advice. You can certainly drive up under the porte cochere, unload your passengers and bags, and then park your car in the self-parking area.