Hi Strima77
Why not the Spiegel Grove AND the Duane. These are great wrecks and are very different dives with distinctly different character. Both have many easy swim throughs. mike s is absoulutely correct, my usual max depths of 100-110 feet are not much different but my average depth on the Spiegel is just less than 70 feet whereas on the Duane it is just a bit less than 80 feet. Both are perfect for 32% nitrox, giving you about a 45 minute total dive time for the Spiegel and more like 40 minutes for the Duane. I second mike s's suggestion for the Benwood also. It's usually very fishy and the max depth of 50 ft and avg depths of about 30 feet make for nice long, leisurely dives. There's a nice mini-wall to about 80-90 feet a short swim SE from the bow.
The water in December is often in the mid-70s. I usually wear a 5mm, especially when diving 4 dives per day, and stay toasty.
As an example, Ocean Divers does a wreck and a reef every morning and 2 reefs each afternoon. On Sunday, you can do the Spiegel in the morning and the Duane in the afternoon, both with a reef 2nd dive. In a couple of days you can get in both wrecks and several nice reef dives (Benwood counts as a reef due to shallow depth). OD will go out with 2 divers. I'm sure many operators run similar schedules and can deliver the same array of great dives. Enjoy Key Largo.
Good diving, Craig