The studio pant from Athleta are so comfortable, you'll want to put them on when it's time to wind down from the day.
These aren't the only pants like this; over the years I've seen them in various stores — the important part here is that they not have any kind of elastic waist band — they should be very soft and something you want to put on at the end of the day. You may have to look in the maternity wear department.
Update: Athleta now has a "jogger" version with a band around the ankle so that you don't have as much flowy fabric to deal with (a more sophisticated alternative to the option of tucking your pants into your socks, which my family members have been known to do). I would get them in "tall" because these seem to be intended as high-waters, which loses some of the luxurious vibe for me.