Dunno what year your Leaf is, but 450 miles will be quite a planning exercise in a base model unless you have the CHAdeMO fast charge port. Otherwise you'll need to plan the trip around L2 chargers in range (and a lot of thumb-twiddling while you charge up, L2's take 4~8 hours). If you do have CHAdeMO, some useful advice:
* In case of trouble, plan ahead to keep Nissan dealerships within a stone's throw and not just L3 charge stations.
* In a pinch, an Infiniti dealer can do most repairs on a Leaf except for the drive motor and transmission. They won't have the most Leaf-specialized equipment, but they can access all the Leaf manuals and bulletins, will have all the normal Nissan special tools, and will probably have an HEV-certified tech on staff.
Also some general advice from a seasoned road warrior:
1) Never miss a piss.
2) Reduce liquid consumption to a minimum (see rule 1).