One more suggestion re: cartomizers. Get the XL size for the eGO. They fit the Riva as well. You can add more juice to those and they'll last much longer than a standard cartridge.
You'll get some cartridges and atomizers with the Riva kit, so if you like those, that's good too. The cartomizers are an atomizer and a cartridge in one, so less fiddling.
You'll at least have cartridges/atomizers AND XL cartomizers, and can decide from there what you prefer.
You "could" get yourself a Riva kit and an eGO USB Passthrough (but you'll need a USB car cigarette lighter adapter if your car doesn't already have a USB port right by you), and then vape while the battery is charging, plus have the backup Riva batteries.
All of the atomizers/cartridges/cartomizers mentioned above will fit the eGO Pass through too. Riva is a rebranded eGO.
Put me down for the Liberty Flights bandwagon too.