Decisions, Decisions!
Seems like in the quilting community there are always discussions on how much? what kind? of things! One of those is type of quilting. No, I'm not talking about whether to hand or machine quilt, cause as a long arm MACHINE quilter, I always vote for machine! But even then, you have to make some choices.
First up--is the question of "how to quilt". My first answer to that is "what are your plans for this quilt?" If this is a wall hanging and not likely to be used much and rarely washed, I'd say "go for it!" Quilt it to death! This is especially true when the wall hanging has embroidery work, applique or other features that you want to really POP! The denser quilting around the features will make that happen. Also, the density of quilting will help that wall hanging hang flatter. Often with applique or embroidery work I will quilt closely around the feature and then quilt a dense fill in the background area. Of course, with that denser quilting, it's important to be sure to adequately quilt the borders so that they don't curl or wave.
Bed quilts typically need to have more "cuddle" and drape. So while quilting still needs to be spaced only as far as the bat allows (wool and cotton and cotton blends usually no more than 4" apart; poly sometimes as wide as 8"), that could be just one curved lined versus an involved feather or flower.
If that quilt is destined to be a lap quilt or a child's quilt, then the chances it will get more washes goes up--and so should the amount of quilting! In these cases, the quilting should cross all fabrics, regardless of the density required by the bat. (and remember--NEVER hang a wet quilt! That is a sure way to pop thread stitches!--lay it flat or put in a dryer).
The next question asked is "do you want the quilting to really show or do you want mostly texture?" If you are wanting contrast, then using a contrasting threat will sure help with that. Texture calls for same color thread as the fabric--which could add some cost to your quilting is there are many thread (color) changes to accomplish that blending.
Of course, you need to let your quilter know if you love or hate feathers; like simple designs or want some really involved motifs in the blank spaces, etc. I sometimes get clients that will say "do something modern" or " I hate modern!"--what they are usually referring to is more geometric motif shapes--but you and your quilter should make sure you have the same definition when talking. And hopefully you will have a quilter that can be upfront with you on what he/she does well--I recently had a client say she loves ribbon candy motifs--unfortunately, mine tend to evolve into pebbles so when I told her that, we nixed that idea.
Here is an example of simple quilting on a quilt destined for a lap quilt or a child--dense enough to hold together and yet not stiffly quilted.