For a '94 I'd start with the switches themselves - I've looked at several different makes of vehicle and in my experience the problem is usually a dirty switch - and yes - one faulty switch can cause both switches to stop working.
Start with the individual door switch - it can usually be pried out of the door with a small screwdriver and then very carefully disassembled and cleaned, they are plastic and snap together - this doesn't need electrical skills as such, more the ability to take things apart and reassemble them, without breaking them - usually you'll find a set of contacts that look scorched or blackened, I use a very small wire brush in a rotary tool and then finish up with a switch cleaning spray.
The switch cleaning spray by itself works, but the problem will come back in a year or so.
Please bear in mind that it could also be a broken wire or even a defective motor, but in my experience, the switches are the most likely cause.
The above does not hold true for all power window systems, but Suzuki used a very basic control system up until around 2002/2003 after which they complicated it with a microprocessor - other manufacturers went the microprocessor road much earlier.
