USB to serial converters only work most of the time. There is at least one very expensive solution which is said to work good with laptops. There is or was a KVM like solution for serial lines from HP ...
As part of our network redo another thing we are thinking of adressing is our KVM solution. Right now we have a number of Avocent 1750R and 2000R IP KVM switches, and some really old school Cyclade ...