I am living at home now, and my parents have a landline for the alarm system and reliability. I try to get them to drop down to the very basic service, not the rip-off long-distance, but they won't. It is useful to have a line that will work in a power outage, as through the hurricane last year, AT&T landlines were rock solid, with battery-diesel power at the CO.
We have iffy cell service, and we have a Microcell to get good service inside, which works pretty well now, but if we have a power OR Comcast outage, the M-Cell is dead, so it's about the first thing to go.
When I move out of the house, I will not have a landline. I was toying with getting an Ooma line, but really, I barely use the phone, and I have my iPhone with me EVERYWHERE, and I probably won't be home that much, so it's just not worth it. I probably will get a Verizon (PagePlus or Trac) burner though just to have better reliability, since they stay rock solid during power events, while AT&T is a hot mess with any power instability.
At work we have landlines, but our new office has VOIP phones from Cisco.