The only "permit" that would allow you to carry in all 50 states is a law enforcement ID
As previously mentioned, Illinois and Wisconsin have no provision for citizen concealed carry.
A large number of the new england states along with several other states do not recognize any other state's permits. Some can technically issue permits but either issue no permits or are extremely restrictive. Many states will not issue to non residents at all.
The state that has the best reciprocity (as discussed in another thread) appears to be Michigan. Michigan only issues to MI residents however.
If you want to test combinations of licenses, the handgunlaw.us website has an application at
http://www.handgunlaw.us/LicMaps/ccwmap.php where you can enter multiple states and the map will show you the reciprocity coverage. Also be aware that 5 states (FL, SC, MI, CO, and NH) will only accept reciprocal permits from residents of the state where the permit is from. So if your home state isn't good on permit issue or reciprocity, you're SOL for SC, MI, NH and CO as those states do not issue non-resident permits or require a permit from your home state.
We've had a couple threads in the previously linked carry forum to explore reciprocity with multiple permits. In the same vein, if you would give us your state of residence and where you typically travel to we can suggest some options for permits for maximum coverage.