I’ve complained about the astral plane before: I never had a use for “a great, endless sphere of clear silvery sky” which is primarily used to get to more interesting places. However, I found myself using an astral plane in the mearls sidebar game, with one little tweak.
Your perception of the astral plane is determined by how you enter it. For instance, in the sidebar game, you dive into a pool to travel to the fairy realm. Along the way, you pass through the astral plane: since you enter it through a pool, it takes the form of a vast ocean. Elsewhere in the world, a forgotten corridor in a library might lead you into the Astral Plane. In that case, you’d experience the entire plane as an infinite, labyrinthine library.
The advantage of this change: Every time you enter the plane by a different method, the DM can describe it differently, coming up with a unique, and potentially flavorful, setting with new puzzles and challenges. An Astral spell might take you to the standard, boring silvery-sky plane. The magical rings from Magician’s Nephew take you to a forest, an “in between place” filled with portal ponds. An astral ship takes you to the 4e version of the Astral Plane, a silver sea dotted with islands. If people entered the plane by each of these methods, they might perceive the same group of githyanki raiders as simultaneously flying through the air, running through the forest, and sailing a ship through the ocean. Each perception is 100% factually correct: after all, any physicality in the Astral Plane is just an analogy clothing an ineffable spiritual ideal.
Here’s an adventure complication: you find a map of part of the astral plane. It’s a classic pirate treasure map, with islands and shoals. When you enter the plane via a library, you have to navigate the Astral Library using your map of the Astral Sea.