My suggestions

I'd do a charcoal gray or a dark brown.

http://www.oldhouseguy.com/all-about-shutters/

Thank you Denita, this is an interesting website!

You're welcome. I think it's an interesting website too.

Thank you Patricia! We'll keep the white siding for sure - the expense is too great to change that right now. I'm leaning toward brown shutters, but we'll see if the house without shutters grows on us once the siding gets a good scrub. Unfortunately our street doesn't allow mailboxes near the entry of the yard and needs to be near the front door (mail is hand-delivered here on foot!). I wish we could move it! I really like the idea of a larger stoop and pots of plants to frame the area.

Which red are you using for the front door?

Here is an interesting article on which red to choose: https://www.kylieminteriors.ca/best-paint-colours-front-door/

Another article with different reds (and other front door colors): https://www.housebeautiful.com/room-decorating/colors/g558/front-door-color/?slide=13

Thanks Denita! I painted the door January Garnet by Behr. It's a nice deep red, no pink/magenta tendencies: https://www.behr.com/consumer/ColorDetailView/HDC-CL-11. Thank you for the links!

Lady Grey, I feel that your front door color gets lost behind the storm door. If you keep the storm door, it should be painted to match the door.