The hours drop downs are available in the advanced form as well. Just in month view when you want to insert the appointment the "Allday" checkbox is checked by default. If you uncheck it the hours dropdowns are shown and can be changed as well.
the Telerik team
If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to their blog feed