The most versatile, trickable features are:
-Flat down
-Flat
-Down
-Urban style down
-Trap
-A-frame
-DFD
-FDF
-Dragontail aka Wailtail
Rainbows, though fun, aren't very trickable. I do not think they should be a priority in a park, especially one thats just getting going. A saddle box...