:) Finally got the courage to design my own PCB from scratch. It's basically a breakout for 2 * 16 channel GPIO MCP23S17 extenders. So the I/O pins lined up I decided to mount the 2nd IC on the reverse side so the main signal wires can be kept nice and straight and to avoid unnecessary rat nests.
It has the ability to chain boards together and I went with solder pads to allow the address of the chips to be selected rather than hard coded. The 16 pins of each chip are in groups of 3 to make it easier if using RGB LEDs. This chip has no PWM but is very cheap and comes in the easy to solder (so be it larger) DIP size. The 7 different color combinations + all off is perfect for my needs and budget.
To make it more flexible no resistors are added to the board... these would be added in-line on the wiring.
I'll can make the schematic etc available at some point when the board has been tested.
The circuit has a single protection diode which seemed to work on the breadboard. Was wondering if I should bother with a capacitor between VCC and GND... I suppose if I make space for it they can be optional.