Recently I was tasked with generating service areas for two locations in Los Angeles. The customer wants to see the visual difference in the service areas based on the time of day the traveling nurses go out. They aren't supposed to go beyond 30 minutes of the facility so they are trying to determine visually the best time of day as well as day of the week to go. I am working in 10.0 and have ESRI's Streetmap Premium Advanced (NAVTEQ) but do not see an interface to allow you to enter the time of like you do in the routing analysis. Is it even possible to do what has been requested with what I have? My end goal was going to be generating service areas for Monday thru Friday every hour between 0800 and 1600.
There is another option for you as a 10.0 user...As long as you have 10.0 service pack 5 installed, you can use the GenerateServiceAreas ArcGIS Online geoprocessing service. (10.1 users with service pack 1 can also have this option.)
Once you connect to the service, the tool shows up in the Catalog window of ArcMap. It looks and acts like a GP tool, but it has a high-quality road network dataset built into the ArcGIS Online service, so you don't need to add a network dataset to your map.
Once you're connected, add a basemap, add your facilities, then open the tool, which will be in the Catalog window under GIS Servers > arcgis on logistics.arcgis.com > World > ServiceAreas > GenerateServiceAreas. The side-panel help of the tools dialog box should help you along, but let us know if you have any questions.