Motorola have the 'Coldfire' series of micros which are a streamlined version of the 68k instruction set as well as a few 68300 series embedded controllers.

Yes, the instruction set was nice. Nowadays, I try to avoid using assembler as there are many micros with sufficient resources to support C without too much of a performance penalty. Even the humble 8051 is a fair candidate. If you want more bits, look at the ARM based cpus like philips lpc21xx series. The ARMS have an interesting instruction set - in the ARM mode, most instructions have conditional execution and three way instructions : R0 = R1+ R2 type things. It is a load/store type of architecture ie: you can only read or write to memory, operation are done on the internal registers.