[pct-l] Favorite middle layer?

[Braden Snapp]

I'm planning a long trip next summer and am starting to get together the
Christmas wish list.  Wondering what people use as a middle layer top in
summer.  I've used wool sweaters for 15 years (pretty much the same
sweater), but almost everything I read and most of the merchandise is
fleece.  I'm also trying to cut down weight as my knees can no longer carry
the kitchen sink.  Looked at the Mountain Hardware Microgrid Zip tee (10.8
oz) - (is it warm enough?), Northface SDS 1/4 zip (14.6 oz), and the REI
Woodland fleece (too heavy/hot?) 19 0z.

Thoughts?  Favorites?  I'll have the Smartwool microweight long sleeve and a
synthetic T as alternating baselayers for cold and hot days.  Just thinking
about a mid layer for passes, mountaintops and setting up camp at night.

Thanks!