Avenir, Avenir Next with Baskerville in action on 2013.withassociates.com

Under the hood

.header-1 { font-family: 'Avenir LT W01 35 Light', sans-serif; font-size: 16px; font-style: normal; font-weight: normal; letter-spacing: normal; line-height: 26px; text-transform: none; color: #FFFFFF; }
.header-2 { font-family: 'Avenir Next LT W01 Bold', sans-serif; font-size: 65px; font-style: normal; font-weight: normal; letter-spacing: normal; line-height: 69px; text-transform: none; color: #FFFFFF; }
.content-1 { font-family: Baskerville, 'Baskerville Old Face', 'Hoefler Text', Garamond, 'Times New Roman', serif; font-size: 20px; font-style: normal; font-weight: normal; letter-spacing: normal; line-height: 36px; text-transform: none; color: #3D4349; }

Avenir is available from Fonts.com and MyFonts.