Jo, I'm surprised you don't recognize Calling_All_Angels' icon of...yep, and Angel with wings!
As for all you people showering in the hospital, all I can say is LUCKY YOU! I don't know if it differs country to country or if I just had a sadistic surgeon, but I wasn't allowed to shower until 24 hours after my staples came out! Yep, two weeks of sponge baths. I think my first shower I exhausted all the hot water and still hated to finish! My home health PT taught me how to get in and out of my shower (for when the time came), and the one thing everyone insisted upon was one of those grab bars to hold on to while in the shower. Fortunately, I already had one from the previous owner. I have a tub/shower combination, and frankly, a shower seat would not fit very well in the tub. I had talked with the occupational and physical therapists, and the concensus was that it probably was not necessary...and it wasn't. I found my new knee was incredibly stable standing, even when I could not walk on it unassisted by walker or cane.
Personally, I'd opt for the raised seat on the toilet, with arms if possible, or a vanity or walker or something nearby to assist standing and balance initially. I was able to use the vanity next to the toilet to help me stand at first, and then one day I realized I'd been standing up without leaning on anything! Love those small accomplishments
Go with your instincts...if you are in otherwise great shape, you may be able to forego some of the temporary aids like shower seats (but definitely get/use a secure grab bar!), but if you question your balance, leg strength, or upper body strength, look into what durable devices would best assist you in your recovery.
Good luck with your surgery, and please keep us all posted on how you're doing!