Engineered will save you a lot of money while still providing the look you want. Of course there are benefits to solid hardwood, but we believe the ease and price of engineered hardwood outweigh them.

We recently went to a couple open houses of newly built homes with engineered wood floors. While we liked the floor they chose, we were not so happy with the significant gap between a number of the planks. Is this just a bad installation or is it due to it being engineered wood instead of hardwood? Our hardwood floors don't have that kind of space between the boards.

gaps bigger than the width of a credit card are from a poor install, assuming it was just installed. older floors with larger gaps are a different story.

Can you be more specific? Are you looking for random or alternating widths? What type of wood? What color? Do you have enough space to do a subfloor in the first floor areas if you decide to use solid wood? Prefinished or site finished? What are the humidity ranges the floor will be subjected to?

We could step down the concrete if we need to,humidity is 39-91 with a avg in the middle,looking for a light or even whitewashed Scandinavian look,clear white oak maybe,random lengths is fine,it's going in a more modern style interior,we also don't mind a few flaws as we have 3 kids so we need it to age well.

One other suggestion - check out oil finished wood floors. They hold up to foot traffic really well compared to a semi-gloss or gloss polyurethane.

Bamboo all the way, hard wearing, looks great and good for the environment

The humidity you quoted is probably exterior. I assume interior humidity would be in a narrower range. Solid wood is nice but there can be issues when you have wide humidity swings or very minimal humidity in winter, especially with wide boards. There are some high quality engineered floors with substantial top veneers that should outlast you and maybe your kids, with proper treatment. Look into products from Owens/Quanex or similar. Owens offers White Oak in widths from 3" through 8", in standard or upgraded lengths.
For information, when you say "clear", please note, this is a standard flooring grade, specifically in solid Oak flooring. Clear grade wood isn't used much, and generally has minimal or no cosmetic flaws. Select and Better is generally sufficient for most people.

I really like Owens, never had an issue with it.

I'm having quite a run on it. 1906' of 8" White Oak, 2' to 10' inbound, a nice little order of 7" Brazilian Cherry I'm going to pair with 1/2" strips of Maple for a nautical look, a small job of 3" Brazilian Cherry and a decent job of 6" White Oak all at once. I hope this trend continues.

all in owens? Damnnnnn money bags :)

The following floor type should work well for your need.

Solid Engineered Floor

I live in CA and chose engineered floors. We are now having a problem with the stairs because we can't make them from the engineered flooring. I still love the floors we picked (and factory finishes tend to be more durable than applied finishes), but I would think through the entire flooring choice (stain, stairs, etc) before you make a decision.

I am in Oklahoma as well and have 5" solid hardwood floors on half of the first floor. We've been looking at doing wood floors on the second floor and have been struggling with the same issue. We actually have gaps in our floors, some bigger than others, that are more extreme in the winter. I am told it's because with solid hardwood, you have to leave space for expansion and contraction. It drives me crazy!!!

Good thing about engineered is that the color you pick is what you get. We are looking into refinishing ours and have been told by multiple people that it's sort of a trial and error thing for getting the color you want when staining existing wood. Also, you apparently can't get as dark of a stain on solid wood as you can buy with the engineered.

Below is the manufacture's description of this product which serves all the purposes of engineered and solid wood floor. For qbryant's situation, you could nail down this floor on the upper level and glue or float it on slab of lower level.

"The Solid Engineered hardwood flooring with a total thickness of 3/4" and a 5mm sawn hardwood face is built to endure any interior condition and are meant to last a lifetime! This winner beats every solid wood flooring and shows a much better stability (up to 75% reduction of shrinkage and expansion) while thick wearlayer rivals any solid floors.

This manufacturer uses the most stable construction. 3-ply design, with a solid sawn hardwood face, core and back creates a balanced product that stands up to the toughest environments worldwide. Installation is applicable in any living level, under a more broad range of moisture conditions and warranted over radiant heat."