A bar is one of the few pieces of cabinetry that is meant to be looked at rather than looked past, so it gets treated as a feature rather than as storage. That changes the decisions. The back of the bar carries the material you want people to notice, whether that is a mirror, a timber veneer or a stone splashback running up the wall. The front carries the finish that matches the room it sits in.
Then it is the practical side, which is mostly about glassware and ice. Stemware wants to hang or to stand on a shallow shelf where it is not stacked and knocked. Bottles want a run deep enough to stand upright, lit from above so the labels read. A bar fridge or an ice drawer needs ventilation that is designed in rather than a hole cut afterwards. If there is a sink, it wants a bin beside it, because a bar without a bin becomes a bench covered in bottle tops.
We also plan the standing room. A bar that is beautiful and two hundred millimetres too shallow to lean on gets used once. Where the room allows it, an overhang and a couple of stools turn the bar into somewhere people actually stay.