All of the people I work with who are senior to me are very nice.
All the people above me at my workplace are so nice to me.
ーAll of the people I work with who are senior to me are very nice.
「職場の先輩たちはみんなとても優しいです」
people I work with who are senior to me で「職場の先輩たち」と言えます。
ーAll the people above me at my workplace are so nice to me.
「職場の先輩たちはみんなとても優しいです」
people above me at my workplace でも「職場の先輩たち」と言えます。
ご参考まで！
「職場の先輩は皆優しい方ばかりです。」は英語で「All my seniors at work are very kind.」と言います。 "seniors at work" は「職場の先輩」を指し、"very kind" は「とても優しい」という意味です。
他の表現方法としては：
My coworkers are all very supportive.
Everyone senior to me at work is really nice.
カナダ 
アメリカ合衆国 
