It depends on a number of circumstances for me.

- Is it busy at the hotel? Could be due to an event, holiday, etc.
- What are the alternative hotels like?

If there's no reason for them to delay answering, which can be hard to know as they might have a private event at the hotel that is keeping them busy, and there's another hotel I wouldn't mind staying at I would move on.

If I know, or suspect, they might be busy, it's an outstanding hotel or my question isn't all too important then I'd send another e-mail trying to send it at a time that should work well according to their timezone and hope they get back to me. If they still don't, I would most likely rethink the whole situation.