Sleeping bag tips requested!

Anyone use a vapor barrier or sleeping bag liner? I'm looking to add a little extra warmth and reduce risk of a wet down bag. I already vent my 4 season tent, use two sleeping pads, wear clean/dry clothes, and try not to breath into my bag. Yet I always end up with a damp down sleeping bag.

I have looked into vapor barriers some but it seems like you wake up a clammy mess. The sleeping bag liners all seem to be so-so.

Any tips/comments/suggestions are welcomed.

I used a vapor barrier liner in my sleeping bag for a week long April ski trip to the Wind River Range (overnight low temps around 0F)  and also on a five day ski trip into the Enchantments.  I used one home sewn from coated ripstop.  The vapor barrier added maybe 20F to the warmth of my sleeping bag and quite noticably kept my down bag drier and fluffier over the course of the trip compared to my companions -- even those with synthetic bags.   The down side of using a "whole sleeping bag" vapor barrier is that you are limited in how much extra clothes you can wear inside the liner -- as anything inside the liner gets damp.  I would dry socks by placing them outside the liner, but inside the sleeping bag on my stomach.

This season I've been experimenting with using semi-breathable vapor barrier clothing layer "next to skin" while touring (Marmot Mica Jacket and Marmot Essence pants).  The results are interesting and show some promise.   The vapor barrier adds considerable warmth and wind-proofing -- and also protects insulating layers from sweat during hard efforts.  I've only used these day touring so far, so I'm uncertain whether the "semi-breathable" approach will help keep a sleeping bag dry during a mult-day trip (since the semi-breathable layer allows some moisture transport).  One nice thing about using a "next to skin" vapor barrier is that it would allow wearing a down jacket and pants within an oversized sleeping bag (or under a down quilt) -- saving overall pack weight and making getting started in the morning much more comfortable.

I just build "drying time" into my daily routine for multi-day trips. When there is a sunbreak, or a light breeze, you'd be surpised how quickly a hung-up sleeping bag will dry out, provided it isn't soaked.