Getting to Portofino from Genoa is quite easy. Take the train from Genoa's Brignole Station to Santa Margherita Ligure, and then catch the 82 bus to Portofino (a 12-minute trip around the bay). While I'm not a huge bus person, this is one of the most gorgeous bus rides I've ever experienced.
A tiny fishing village with a very posh clientele, Portofino is a wonderful day trip—perfect for walking around, shopping at high-end boutiques, and enjoying an apertivo dockside before heading back to town. Yet Portofino is also covered with trekking trails, so another option is to wear walking gear and come for the breathtaking hikes!