I have completed my move to full frame, but tried many of the above lenses on my Rebel bodies in the past. The Tokina 11-16 f/2.8 is great on APS-C in terms of price and image quality, and your note about the EF 400mm f5.6L is a good one to include. It's a tough lens to learn, but gives great shots if you can live without IS and use a sturdy tripod and good technique in lower light levels. The EF 24mm f/1.4L II USM is an amazing lens and close to a 35mm on APS-C. I loved it on the crop and love it on my full frame alike.