"set disassembly-flavor intel" was one of the first customizations I made to gdb when I started using it in anger.

Turbo Assembler!!! I think that was pretty much the standard in the demoscene, at least in my circles. I wrote most of our DOS demos with it. Anything that ran in real mode, doing all the wild things like modifying code loaded already in memory... Then for actual 32-bit code (using protected mode) watcom c+asm compilers became the go-to. I still hand rolled some assembly, but with the advent of Pentium processors, their pre-fetch and dual pipeline execution watcom C did a fairly good job to compile highly efficient/optimised code, so asm coding mostly went away. (did use it later professionally for microchip controller programming though) As for nostalgia, I'd rather pick up a virtual console nowadays. The limited resolution, colours, etc. gives enough mental exercise without going back to x86 asm. :)

Setting a breakpoint in the debug registers DB0 through DB7 and dumping registers and memory in your own debug exception handler.