You can pretty much use any of the methods that you posted. It all depends on costs and how much configuration you want to do.
In all of this I’m assuming that you don’t have any redundancy in the network switches. If you want everything fully redundant pretty much double all the switch and port counts.
If you put a switch in each rack you will need to purchase 25 small switches plus a couple of large switches. This makes the cableing easier, but it does limit you as you only have a single physical network available in each rack. If you have a seperate physical DMZ then you will have to have all the DMZ machines in the same racks. Adding more ports to a rack is easy, as you just need to drop in another network switch.
If you use patch pannels you have a lot of flexability as to your physical switches as you have a few high end switches running everything. However if you need to add more ports to a rack it’s harder as you now need to put another patch pannel in place. From what I’ve seen this is usually the prefered method as it’s a much cleaner look, and the power requirements are less (a couple of large switches will take less power than 25 smaller switches, especially since you still have the large switches running the small switches).
If your AC is running under the floor you should put at little as possible under there. The more cables there are under the floor the more stuff is getting in the way of the airflow. I would get some cable trays and mount them above the racks for the network cables.