I've written about wearing lovely things to sleep before (http://hearth-tobelovely.blogspot.com/2011/10/pretty-inside-pretty-outside.html) but hadn't focused on a couple of key thoughts.
1) Wearing something truly lovely to bed is a gift to your spouse.
2) Wearing something truly lovely to bed means that you won't be wearing it much after you get up in the morning. Perhaps for a cup of coffee or tea - but that's all. After all, can you imagine frying bacon in this: http://www.antiquedress.com/item6918.htm ?
3) Wearing something truly lovely to bed makes a little separate space in your day, where you are intimate, vunerable, and beautiful.
Lovely things don't have to be uncomfortable things! I made myself that nightgown eight months ago, I wear it constantly, and it's as comfortable as the day I made it. Because I used a natural fiber, it breathes and doesn't get too hot. Because I used a relatively washable silk, I can hand wash it occasionally (would you want a dry-clean-only nightie?) (Lots of things can be washed by hand and drip-dried, btw).
If you happened to be a pajama person instead of a nightgown person, how about a sexy set of lounging pajamas? http://www.shopinsilk.com/Womens-pajamas/Long-sleeve-pajamas-set/Autumn-Luxurious-Womens-Silk-Pajamas-Set-S-1435.jpg
If you're a cotton gal - how about a sexy short nightie with a bit of lace on the top?
Of course everyone is going to have their nightwear for "I'm sick/cold/exhausted". I have a couple pair of yoga pants that I keep in the back of my stash, just for wearing under a flannel nightgown when I'm truly unwell.
But the rest of the time? At least give a thought to the lovely... you might be surprised by how it makes you feel.