I'd go to Sherwin Williams website and upload your photo. You can try each idea and see how it looks. I think it always looks best to do 3 shades instead of just two.

I would paint a few samples on the house and then decide. Grey is tricky. We recently painted our siding and trim a light gray, and it looks great!

I will get some for you tomorrow :)

We used Benjamin Moore's, Stonington Gray.

Gray with blue undertones is not going to work with this stone and roof - we have a good example here on the boards of what that looks like - the blue grays make a golden brown roof flash off orange and make the stone lose its power . . https://www.houzz.com/discussions/exterior-paint-dsvw-vd~3042046

keep your siding near what it is now - so the house looks tall and flows. Do contrast this with a deep warm gray on the fascia and trim something in the equestrian gray (ben moore) world will work well. Siding - test colors to match what you have - possibly near bm senora gray . . .. the color that is on your house is a really good tone for it - what you can do is call out the window trims, and paint your front door an accent shade - a terracotta door would be very pretty . . test ben moore montana agate http://www.benjaminmoore.com/en-us/paint-color/montanaagate

http://www.benjaminmoore.com/en-us/paint-color/equestriangray

I tried to get some good pics. We just had tornadoes and cross winds go through, so ignore the random twigs in the yard as we're picking up. Our brick has more blue tones in it.

Same for fascia and trim usually . . let me look back

Yes.

If the base color reads yellow to you, you can definitely shift to more of a putty tone. Senora gray was one suggestion that might be close but what you are trying to do is match the undertone of the stone overall - you can do that a couple of different ways - senora gray is kind of an olive undertone putty you might test but look at many until you find a natural tone that works with the stone and your eye. Test colors on a big board you can carry around outside -