In Bleach, there are times when we see Soul Reapers (and Visoreds) stand in the air. Examples are like when Ikkaku releases his Bankai during Grimmjow's initial attack, when Shinji first reveals himself as a Visored to Ichigo, or way back in Season 1 when Ichigo was fighting Sora. This was also mentioned by Kisuke when he was training Ichigo where in Lesson 2 - Shattered Shaft he says that Ichigo can get out if he flew out and the purpose of Lesson 2 was to restore Ichigo as a Soul Reaper.
However when we see Soul Reapers fight in the Soul Society or in Hueco Mundo we don't see this. We don't see Soul Reapers standing in mid air to get a height advantage on Ichigo and his friends when they went to rescue Rukia and so far (up to Episode 157) I have not seen Ichigo, Rukia or Renji fly.
Both the Soul Society and Hueco Mundo, as stated by Uryuu, are rich in Reishi. So I am wondering, does a Reishi rich environment prevent flying?