We are fortunate to have a large double walk-in shower. I'm using a PVC garden chair, it has a high back and sturdy arms for pushing myself up, as well as slots for the water to drain. I feel very secure in it. I also use an old walker with a cup holder in the shower. Not only does it make me feel more secure when making the two steps to get out to my waiting rollator, I can prop the handheld shower spray in the cup holder so that it's within easy reach as I shower. My friend gave me a long handled sponge which is great for reaching my feet or back. (Helps in chasing down the soap too) A plastic suction cup holder keeps the soap at my level and easily reachable. Another larger one holds other shower necessities. I use a rubberized cloth for drying a car (Auto department of W'mart) as a floor mat when getting out of the shower. It's less slippery than the grippy shower mat I bought for that purpose. Most of the drying gets done in the safety of the garden chair before I exit.
Did I mention there's even a heater in the ceiling of the bathroom? We may live in the south, but that's one feature I don't want to lose, especially as it takes so looooong to shower and dress. These days I'm finding it much easier to do part of my dressing seated on the bed with my rollator in front of me.