My dad is the ultimate in reserve -- happy, sad, scared, angry, he keeps everything to himself; most of the time all you'll get out of him when you ask a question is an evasive, noncommittal, or just plain absurd answer. While it's charming and witty, it can also be very frustrating, because you never know what he really thinks about anything. In every conversation, on every issue, even on where he'd like to go for Father's Day, dad abstains.
My parents are like yin and yang in that respect -- my mom is wantonly garrulous, to the point where people's eyes glaze over the moment she opens her mouth because you know she's not actually going to say anything for about 15 minutes. My dad generally just points her at people and says, "Go!" then sits in a corner amusing himself while she runs conversational interference. For the outside world, it suits them as a couple, but it wreaks havoc on a father/son relationship because when mom's around, dad isn't, even if he's sitting right next to you. Is this the source of Tiffany and Conrad's absentee dads? I dunno, I suppose it could be.
I do love my dad, and I'm making an effort to spend time with him while I still can. He's going to be even more gone than he always is soon, and that's not going to be an easy thing for me.