as for length, I've read that it should be 2/3 of the width of the bed. as for the depth, i would want to leave a 36" path between it and a wall or another furniture piece. that is my opinion, others may have a published source for the dimensions.

maybe consider an ottoman that's thin and long if you can't find a true bench.

I need a storage bench for all the pillows at night .

that's going to be a tough find, maybe consider another storage option for you pillows?

@interior design yes I just couldn't think of anything that would look modern enough to go with the style of the bed

using a 'reclaimed wood' shelving system might be a cool juxtaposition with the femininity of your upholstered bed, then you could just stack or line up your throw pillows on the shelves?

Here are some bedroom images from our design portfolio. There are many benches at the ends of the beds.