I have to explain the second one. You could do a lace-up back. At johann's right now (at least where I live) there is lace that has holes in it to put ribbon through. You could sew that right on the back. What would look better would be the pannel trick I drew on the right.
For this approach, the procedure is a little more complex, but still relatively easy to do, if you can do buttonholes or put in eyelets.
First you have to sew a rectangle of matching fabric (right sides together) and pull it inside out, then on the edge sew buttonholes (or put in eyelets if you can.).
The dark green is folded back and sewn onto the dress along the red dots (as you do that, you have the "fold" opened, like a book). Then "close (the book idea again)" it over to the right side and stich down on the pink lines.
I would also add a layer of fabric underneath each tier, to make it poof a little.
....ramble ramble ramble. XP