I currently run 11-36 on a 32 front ring.

I’m converting to a 11-42 do I run a 32 or a 34 front. I ran a 34 for better gearing when going downhill in France, however does 42 rear to 34 front cover better range than I originally had?

No idea, it’s singlespeed season with me but this may help with the number crunching
http://cycleseven.org/bicycle-gear-inch-calculator

I find this one helps get my head around the numbers

http://www.bikecalc.com/gear_inches

If running a 26” wheel with a 2.35 tyre you were moving forward 23.8” per pedal stroke… with a 34 to 42 you will be moving forward 21,6” per pedal stroke…. you could go to a 36 up front and be moving forward 23” per pedal stroke.

Hope that was helpful rather than confusing!

You need to consider the ratios. No need to worry about much else if your wheels are staying the same

Divide the front sprocket teeth by the rear.

Look at the high and the low and see if the range changes.

Depends whether you want a taller top gear or easier bottom gears as a result of changing the cassette. 32:36 is 0.88 as a ratio, 34:42 is 0.81 so already 10% easier, but 32:42 would be 0.76, so another few % easier again.

Surely a simple ‘yes’ to the OP’s question.