The skirt is knife pleated to the bodice. Does a deeper hem (more than 2") hang better; or is something like 2" preferred? It's for the pink gown I posted a while ago. (https://fbcdn-sphotos-b-a.akamaihd.net/hphotos-ak-prn1/1148812_639973602687854_226479875_n.jpg)
I think it comes down to personal preference. I personally don't like deep hems (I don't like the visible hem line 2" ~8" above the ground) and just roll the edges. Even in period gowns, it ranges greatly from completely bag lined skirt to the narrowest hems.
That will depend on several factors:
How heavy the fabric is
How thick it is
How straight or curved the hem is
Whether or not it had pressed pleats all the way to the hem
Is it sheer?
What the fabric surface is (satin takes a special treatment!)
On that fabric, looking as stiff and heavy as it does, and with a fairly straight hem, I'd give it about 3" so it has some weight.
I don't like to do over 3 inch hems when doing heavier gowns. Lighter weight gowns I usually do an inch. I did a 6 inch hem on a girls dress, and it looked terrible even if I did sew it by hand. Like Kate said, it depends on the dress but I wouldn't do more than a 4 inch MAX.
On my gowns, I have done as much as a 4" hem. But then, I tend to use Velveteens and heavier Brocades. 2" at the most for other fabrics.