[pct-l] Base layers

[Amanda L Silvestri]

Okay, here's a new thread.  I am looking for a new base layer.  I have some light weight long underwear, but am thinking that for the JMT I might want to move up to a mid-weight, especially for sleeping. 
 
Looking at the Campmore "sale-mail"  this morning, I see many verities, but there is little information as to weight-to-warmth ratios.  They all look good as I read their description, but I have no idea as to if one pair weighs more than the next.  
 
Also is there any system for evaluation the warmth or body heat retention ability like there is for down sleeping bags?  Even in a store, I can't go around ripping open the packages.  A double layer with a synthetic for wicking and perhaps a wool for heat, sounds good, but then I am back to weight again.  Oh, and I don't want to but the most expensive brand out there either.
 
Any thoughts?
 
Amanda (Shepherd)