Aviv and
Shai would work for sure, I've known several Avivs (all male) and a
Shai (male).
Rotem would be unusual, but I it's not difficult to pronounce and I don't see something being foreign/unusual as a reason not to use it if it's a name you love.
I see all these names have a decent amount of usage on girls, but
Aviv especially is very masculine to me.
Shai seems pretty unisex, but more feminine in the "creatively spelling the word Shy" variety while the Hebrew name seems masculine to me, probably because the
Shai I know is very masculine. I also don't really care for the fact that I forsee jokes when she would introduce herself as "Hi I'm
Shai" "Haha you seem pretty outgoing to me!" type of thing.
Aviv's a favorite of mine, but for a boy.