I've made swatches of possible stitches that I'll use for this particular piece. The yarn used is Debbie Bliss Cashmerino Aran. I used a 5mm hook and worked a side edging in single crochet (slip stitch in UK). The edging on the right has button holes worked into it.
In the picture below, the 1st swatch was worked in half double crochet (half treble crochet in UK) clusters. The drape is good but it's a little 'gappy' for what I want.
The second swatch was worked in crossed half double crochet (half treble crochet in UK). The drape is good and it's not gappy, however it does go gappy when working the side edging.
The third swatch is worked in trinity stitch. I liked the look of the stitch however its a closed stitch so doesn't drape very well. I may try this again using a larger hook.
At this moment in time I'm thinking of using the crossed half double crochet stitch, if so I'll use a smaller hook when working the edging.