One thing I like about living in the bay area, is there are a LOT of unisex bathrooms, although I've used the mens room since I was 14/15, while out at a bar it sucks waiting in line 10 mins to use the piss covered toilet. I think I might get a packer you can pee out of, just to see what it's like to pee all over the toilet seat, ha.
But yeah, use what bathroom you want to use. If it's the men's, walk in, don't look at anyone, and go do your business. Wash your hands, and leave.