There was no offense taken, I assure you.
The problem you're facing is that the functions you want are all not contained in the same simple ICs, as the simple ICs were intended to do specific, straightforward logic functions. We're actually semi-perverting them to get them to do the sequencer stuff at all.
The real answer is a chip that you can tell "Do this..." and it's complex enough inside to do it. A microcontroller.
Doing a microcontroller program is a big step to get over, but once you do, there's a kind of freedom to make it do whatever you want. For instance, one $2.00 chip in this application would:
- read a speed pot directly
- read a selector switch for what kind of operation you wanted - stepped, random, bounce, etc.
- do the selected operation.
The details of how random the random is, what kind of bounce, which direction to sequence, etc. are limited only by your ability to tell it "check the pot reading; turn that into a timer tick rate; now go do the next step; put that out on the output pins; go back and read the pot; etc." My favorite setup is to program the uC in BASIC to to the stuff. It's fast, and relatively simple. I debug the apps by running them in simulation until they work mostly, then put them into a breadboard/plugboard to wring out. Mostly they work the first time.
Or, if we're being completely honest, mostly they work by the fifth or fifteenth time - so I'm not the best programmer.
Any implementations with hard logic like the 74xxx or CD4xxx series is going to be a compromise in functions, limited by what the chips were intended to do, and by how much that can be perverted.
There is an ideal chip - it's a PIC or its ilk.