Just do some teeny tiny meandering or other pattern that flattens out the batting. That provides a contrast to the feathers which are less densely quilted, helping them to stand out.

Very cool.

I finished a quilt recently that called for a very crisp definition of certain parts. I used higher loft poly batting and micro steepling and it really turned our great.

These are pictures of a quilt I recently completed using two batts, Hobb 80/20 on bottom and Hobbs Polydown on top. I used a 50 wt. So Fine thread on top with Bottom Line in the bobbin.

Somebody please correct if I'm wrong but could you do like a trapunto and just double where you want the feathers to show? I recently did this in aheirloom quilt.sorry no pictures of mine this is a picture of Marion's

How hot would this be?

Dottymo, absolutely you could do trapunto. In fact that would be the preferable thing to do if quilting on a domestic sewing machine as opposed to a LA. I can't imagine trying to manipulate a double batted quilt around on a DSM. However trapunto involves the extra effort of using water soluble thread and trimming away the excess batting. The results are most definitely worth the effort. It is too bad the OP is allergic to wool because that would most definitely be the way to go without doubling or doing trapunto.

Double batting is best done on a LA and it mimics the effect, like faux trapunto, especially when doing a tight background fill to get the feathers to pop.

It has been my experience that a shiny thread shows the quilting more as does a high contrast thread. But high contrast will also show every wobble and mistake. I like Glide 40 wt poly or Isacord 40 wt poly for that for shiny.

Here is my example. This one had bamboo on bottom and hobbs polydown on top. I did Mctavishing as my tight backfill. I used Glide 40 wt poly thread if I remember correctly.
[ATTACH=CONFIG]403276[/ATTACH]

I really have no idea. This is the first time I have done this. It is for a local show coming up in a few weeks, so I haven't put it on the bed. However, the quilt doesn't feel overly heavy. I often use two quilts during the winter, so maybe this one will make a great winter quilt.

I know a lot of people who quilt for show use two batts to get better definition, so I wanted to try it. It is definitely great for that purpose.

I just got a Hobbs Tuscany Polyester batt to play with. Not sure how it compares to the Hobbs Polydown. It's about 1/4" thick, very even. I meant it for hand quilting but based on my experience with other poly batts this thick, I'd expect it to go through a machine quite nicely. Thick enough to get great definition, thin and firm enough not to make too many boogers and lumps.

That is a gorgeous quilt...