I use Directv the problem with using a satellite on the road is that you have to find the elevation and the azimuth you can get this from directv by going to this website and enter the zipcode for the area that you are in.
http://www.directv.com/DTVAPP/customer/dishPointer.jsp you will also need a satellite signal meter I broke down and bought a Birddog this is the unit that the techs use I found one on ebay for about $200 it makes life easy I can usually have it going in less than 5 minutes they do sell meter for around $30 or less.
Using the wingard meter works but it is frustrating. I use the Birddog also and only a few places I could not connect to the satellite.
If you have the money you can buy a VueQube it is your dish that will automatically find the signal for you but it cost close to a $1000.
I belive you must also have DC power to operate the Cube. Maybe someone else will confirm that.
I have found that I have been in some locations that my air antenna would not pick up the local channels (Fox, ABC etc.) and fill out paper work from Directv for the national feeds out of New York and LA but this is also a extra cost of about $14 a month.