All a personal preference, I would go tho the supplier and look at samples. Search on line as well as you may find pictures that give you a good perspective of what you are looking for.

We are debating the exact same thing, but my husband is leaning towards 3" and I would like 5". We may compromise at 4. He is very concerned about shrinkage and gaps in the winter. I am not so much.... I think it gives character. I mention that just to make sure you have considered the gaps that will result the wider planks you use.

The wider they are the more movement they have. Something to consider if this bothers either one of you. I've seen both look stunning.

Wider boards move more (well, proportionally to the width), so there is a much greater chance for noticeable cracks between the boards with seasonal movement. That (as well as production efficiency) is why so much flooring in in 2 to 3 in planks.

There's no rule against mixing widths-- I'm putting down a birdseye maple floor in 2-1/4, 3 and 4" widths. It's a more casual look, but I like it and enabled getting the best price from the mill because it allowed them to make optimal use of the material.

Random width is a very good look for informal, rustic and historic houses.

And after all, wood is wood, so it's natural that it moves a bit. It's part of natural materials being natural. It's not tile or linoleum, after all!

Good luck with your project!

Thanks for all of the help. We live in the NE so we are concerned with the gaps. But I'm not sure how much of a difference there is between 4 and 5 in widths as far as the gaps are concerned. I would get a 3" but I want to take advantage of the beauty of the walnut.

It will be beautiful whatever you choose!

Do be aware that walnut will bleach in strong sunlight, so you should expect variation over time.

We have 8-12" so of course I think the wider the better, something else to consider is the length of the board. We have really long boards- some are 10+ feet long.

I live in southeastern Pennsylvania and have random width white pine floors, ranging from around 3" to around 8". Some of our wooden doors expand and contract, but we've never had any noticable floor movement. I suppose a lot depends on your environmental humidity, both exterior and interior. The point about the effect of sunlight on wood flooring is a good one. You can expect variations where there's strong natural light through windows, and where rugs and other coverings are used. How the floors are finished has a lot to do with durability for traffic, spills and lighting. Good luck!

We have 5" white oak. I love the wide width. We haven't noticed gaps between the boards, and we are in our second winter in the house.

We have 5" white oak also. We have had no problems with gapping yet. This was my husband's choice though - I think the smaller widths are every bit as pretty ;)