They are both very, how can I say this, very 'everyday', really boring, for a 40th, surely.
Nothing wrong with a little back dress. They can look beyond fantastic. Simple but amazing.
But really. Are you sure you want to go for something quite so drab, for your 40th?
I posted a very seminal thread , just over a year ago ,and MN was FAB at finding me the best POSSIBLE dresses.
Hope we- will-- find one that suits you perfectly.