I've had this dress for about three years:
www.the-dressingroom.com/item/Great-Plains/Arabesque-Jersey-Maxi-Dress-Indigo/2TX5#
It is an amazing dress. I feel amazing when I wear it and subsequently wear it a lot in the summer.
The problem is that it's making finding other maxi dresses that I like really hard, and I really want another one or even two. I've tried on so many in the last couple of years and nothing has quite fitted like this one does.
So the reasons I think it works are:
(1) it's very heavy jersey and so it hangs it really well.
(2) the skirt is generous without looking like a tent. There's a lot of material basically and so it hides a multitude of sins including the Mum tummy which I've not quite got rid of yet. I'm a size 16-18 so I think about these things 
(3) the colour is great. I'm not very 'girly' and so monochrome or quite grown up prints look best.
(4) I'm tall (5'9") and this dress hits the floor (hurrah!)
(5) I've got boobs and I've got broadish shoulders - so the top half of the dress works really well. Spaghetti or thin straps don't work for me.
Has anyone seen any maxi dresses that are similarly wonderful because I think I might have given up!