What kind of building blocks are most transistors in current generation CPU's dedicated to?
Intel CPUs have the cost directly dependent to size of cache. The amount of die devoted to L1-L2-L3 cache can be as large as 50% or more. So the elementary block for the cache is multiport single bit SRAM cell with write-through/read through path. It can comprise may be dozens of transistors per bit of memory. And how it looks in schematics is possibly a trade secret.

Effectively everyone who buys contemporary CPUs pays mostly for this cache structures, as they consume most of die real estate. Intel and other CPU manufacturers are mostly in business of selling very large raw caches sprinkled with few CPU/FPU cores here and there. There are even DRAM bga solutions which can be soldered as stackable tier on top of CPU chips. One more evolutionary step and all large cpus will start directly compete with DRAM industry.