i'd use the vertex tool: :vertextool:
note: you cannot undo or subtract a selection mistake while using this tool, so be precise or you'll have to retart selecting your verts.
note: accidentally selecting a surrounding brush will cancel out of your current selection. to prevent this, select all the platforms you'd like to adjust and hit "ctrl+h" to isolate that selection, or hide everything else, before starting to select any verts. when you're done, hit "u" to unhide all your hidden brushes.
note: hold ctrl while click dragging over verts to add to your selection. for hard to reach verts, hold ctrl and click them individually in the 3d view.