If you have an iPad with a GPS built-in (what is called the 3G model, not the WiFi only model) you could try Navfree at the link below.
Navmii/Navfree Latest Satellite Navigation Software for iPhone, iPad and Android
You have to have a data connection to search for addresses so you would have to do it before you left the office unless you have a data plan on your iPad or you visit a place with free wifi while out and about such as Macdonalds. Create Favorites for each address when (if?) you find it.
You can download maps for the whole USA or just the state or states you are interested in.
Navfree doesn't have the ability to import addresses or to create multipoint itineraries.
If you're at A it can navigate to B.
It's supposed to be able navigate from B to C while you're at A but I've never worked out how to do it.
The reason I suggested it is because it uses Open Street Map maps which are created by "men in the street" (Political Correctness forces me to say "and women" but I bet it's mostly men who create the maps) as and when new roads are built. They are available overnight on the OSM website and every month or so from Navfree.
There is also PC Navigator Free which runs on a PC. It also uses OSM maps. It is a teeny bit complex to set up. It also updates its maps every month or so.
Navigator Free | mapFactor, s.r.o.
If you want to use the OSM maps directly you can do this using Garmin nRoute on your PC. To get this to work is also complex as you have to install Garmin Training Center and then Mapsource before you can install nRoute. More detailed instructions on how to find and install these apps are available on this website or PM me if you can't work it out.
nRoute is a bugger to use. No where near as friendly as Streets and Trips. Again read this site or PM me for assistance. Search for my name and nRoute for info on how to click and drag a route to multiple via points.
You can go to the OSM web site to get the maps for the area you are interested in. As I recall it's a bit complex.
OpenStreetMap
Or you can go to the website below and specify the area you want and after a day or so they will email you a link to a download that has the map areas you have requested.
Free worldwide routable Garmin maps from OpenStreetMap
As I recall, it comes in a nice neat executable package that is relatively easy to get into Mapsource and once it's in Mapsource you can see it in nRoute.
As much as I dislike the Apple way of doing things, ie lock everything up so tight you can't do anything that they don't want you to, it certainly makes it easy to set things up compared to the other options.
However, nRoute is fully featured mapping software so it's the best one to use. The others are really just toys. They will get you from your current location to a specified point. Only nRoute will let you set up a multi via point route.