IMO Sicily is better booked as a separate ticket, conveniently planned over a journey in Italy.
The highway to Calabria and Sicily is narrow, as YVR Cockroach said, though the A14 and A16, bound to Puglia, are more easily drivable once the plain of Puglia is reached.
Another option with charming coastal towns pairing with inland small villages is the Cilento coast, in the southern part of Salerno area, on the Thyrrenian sea.
The drive from Castellabate to Ascea gives back some truly scenic views.