Hi and welcome. As to what wire to get, It will depend on what resistance you are aiming for, if you want single or dual coils, and what wattage you vape. For lower watts and higher ohms, 28 or 30 ga is probably right. Go on down to 26 if you want low coils and to run some tall watts. The Aromamizer is not a huge machine, you might have trouble fitting 24ga and lower in the deck. And check out
Steam Engine; this is an excellent tool to help you figure out what your coils will do before you build them. If you work with it a little, you can decide what wire you want before you actually buy some.