The last example probably wasn't great, it looks rather ugly but like I said you can get it in different colors, sizes and options. If you are running multiple spans look for the verticals that have parallel keyholes otherwise you will have to stagger your shelves or buy extra verticals.
Hardware stores local here sell a variety of dressed timbers for benches, these can be cut to size so you can have quite a nice steel framed bench if you want to.