We do a couple pool sessions per year. December is our swimmer fitness test as per IADRS. Along with that I throw in an underwater swim (the length of the pool), knots for rope and webbing, as well as 4 throwbag throws (2 bag, 2 coil). January is our "confidence course". I run a line down one side of the pool, across the deep end, and back up the other side. Along that I have snow fence that we'll drop on the diver that he has to cut through, a "Men of Honor" drill where we put together various PVC pipe fittings (some with bolts) to create a manifold, a cut box with fishing line, picture cable, etc, a plastic drum that you need to doff your gear to get through then put it back on, a lift bag, and an out-of-air drill at the end where the diver finishes on his redundant. I know it seems like a lot to get through, but it only takes our guys 10 or so minutes a piece. Of course, everything is blacked out and we have multiple safety divers in the water as well.
Like anything else, just use your imagination and try to be "evil creative". I believe that the harder you make things in the "safety" of the pool, the less stressful a real emergency becomes.