Current VRP is focused on single day trips. There are some fudges / tricks you can make to obtain a route and then manualy apply overnight stops.
One quick win would be to allow a mix of date/time and time only in date fields. I can set breaks on a date/time to extend a route to many days, however if I have a TimeWindowStart1 as 0900-1700 I am unable to solve as a mixture of dates and times in all date fields in the solution.
I don't know what date the route will take me to the site and I do know the office hours are the same all week. If a date is required behind the scenes, any field with time only should be treated as 'today'