my school gym has 2 main surfaces i use. one is a plastic tile walkway. it's kinda slick, and if i do AG walks or different motions with a frisbee on the ground, i do it here.
the other floor is rubber and normally is great for all handbalancing work. there's a little layer of dust on it (they clean it, but it's that dust that just won't go away), and that seems to become a lot more noticeable when i'm trying wide arm handstands. i'll normally take a stomach-facing-wall handstand on this surface and then spread out my hands till it seems decently challenging. i'll just be sitting there, and then my right hand will all the sudden slip an inch or so outwards. this is very disconcerting if i've already found a width that is hard and i've been there for long enough to get tired, because the new width is probably way too hard to handle.