I can recommend "The Kaiser's Pirates" by John Walter. It has great detail about the cruiser warfare away from Europe, including von Spee's squadron, and has lots of photos.
Another good "what if" is von Spee approaching the Falklands in the evening with limited daylight available. Or von Spee bypassing the Falklands and hitting Capetown, where he would have run into HMS Defense & HMS Minotaur.
For ships, I've got all those C-in-C ships. The Bristol type is pretty good, and the Emden looks pretty good too. But the Strassburg type is my favorite of the C-in-C light cruisers. Note that there is some scale variation between the different makers of 1:2400 scale ships. The C-in-C may be the most correct in scale, not sure about that, but the other maker's ship models of the same ship are a little bit longer and wider. I would definately avoid the C-in-C version of Sydney & Melborne. It just doesn't look right to me. I think the Panzerschiffe version of this class is much better. I have painted up my C-in-C versions of this class, but I'm going to replace them with Panzerschiffe.
For doing the cruiser actions involving von Spee's squadron, I'd recommend a mix of Panzerschiffe and Viking Forge. The Panzershiffe models are the least expensive, and they are cast very nicely in resin. Now Panzerschiffe has specific models for Emden and Nurnberg (use Strassburg, not the Konigsberg model as it says on the website). The Pz model for Leipzig is fine too. These are simple sculpts without a lot of detail, but a good paint job can make them really snap.
I bought some Viking Forge models for the British heavy cruisers, and I like them a lot. They don't have any more detail than the Panzerschiffe, are a bit more expensive ship for ship, and are cast in a brittle white metal that can show mold lines. However, the sculpts look more like those British heavy cruisers in the photos than those of other makers, to me anyway. I really like my Viking Forge Good Hope, Monmouth, Carnarvon, Cornwall, and Kent. But the Panzerschiffe versions of these ships are not bad either. The Viking Forge and Panzerschiffe mix well in a collection because they have a similar level of detail.
The alternative is to go ahead and spend for GHQ for as many of the ships involved as you can find models for, and try to paint them in the most spectacular manner you can, including painting great sea bases. I've seen a GHQ version of the Gneisenau that just about took my breath away because the painter was a true master. GHQ has Dresden (Emden class) and Leipzig, but not Nurnberg, has Gneisenau & Scharnhorst, has Good Hope and Monmouth (same class as Cornwall & Kent), has Invincible & Inflexible, has Bristol, but does not have Carnarvon (Devonshire or Hampshire class) or Canopus (grounded in the mud in the inner harbor). So GHQ does not quite have every model, but almost does. For "what if" versions of Coronel or Falklands using HMS Defense, that's also not a cruiser model that GHQ makes. But both Panzerschiffe and Viking Forge have good models for that class. I've got the Viking Forge version myself.
One thing that puts me off of GHQ is the exaggerated ribs on the funnels of German ships, which is meant to evoke the sort of thin railing or wirelike metal bits that ran around these funnels. This huge ribbing is far too dramatic, and looks kind of odd. But maybe a good painter can find a way to minimize this odd feature.
