I've got a pair of the Terry 'coolweather' tights, which are comfortable and have a built-in chamois. They're good from about 65-50 degrees. If it's colder I use Hind Thermal Drylite (or Drylene?), with a pair of bike shorts underneath.
Of course, I haven't got to use either very much for the past two months, because (excuse the rant) every time I have a day off I'm either sick or it's raining. I'm not even sure I can fit into either pair of tights or paddle more than ten miles at this point.