Ground vias also to connect the top & bottom ground planes.
More ground plane area also equals less copper to be removed for faster etching.
A trace width to current carrying capability calculator will show that 10 mil wide trace of 1 oz thick copper can carry 1A current with minimal temperature rise over the length of the trace.
For example, I entered 1A, 10C rise 1 oz copper, 20C ambient, 20mm trace length (2cm, getting close to an inch).
A 10 mil trace is all that is needed.
So 10 mil for mA or uA signals is all you need, and nearly 2A supply current can be met with a 25mil wide trace.
Use ground planes, don't snake ground traces all over the place.
I'm pretty sure there are other calculators which use the latest IPC model where you can enter width, length, thickness, etc. and get a current capacity out of it, but I'm having trouble finding one. Most seem to go other way, start with current etc and get the needed trace width.