Hi,
We are in NC (Charlotte area) and trying to decide the type of wood floor to install for this climate.

First Floor - (300 sq ft - Family room)
So far we decided on the Engineered Hickory Pre-finished for the first floor (Concrete Slab). This is a small area 300 sq ft which is close to the kitchen tile and a sliding door. The first floor tends to get colder than the 2nd floor. Will this disturb Moisture content as I have been reading a lot of cupping and crowning of Hickory floors.

Second Floor - (1400 sq ft)
We were thinking first on Prefinished Bruce Oak Gunstock (3.25 inch wide,3/4 " thick) but have the option to go for a Prefinished Hickory (6 inch wide, 3/4 inch).
Is a dehumidifier really necessary to maintain Hickory floors? Our AC is usually kept at 72 (May - Sept) and Heat 71(Oct - April).

Really confused on whether to just go with the oak for the 2nd floor as Hickory sounds like a lot of "care" and scary stories of "crowning and cupping". Regardless of Oak/Hickory our installer will keep the wood for 5-7 days to assimilate. Am I over thinking this too much?

Thank you all for your input!

Your AC will keep the humidity low during the summer.
Engineered Hickory will be stable and not have significant cupping.
Pre-finished floors can have a very durable aluminum oxide finish. I don't like the penetrating oil finish for anywhere that food is served and is much more in need of care, periodically.
Hickory is significantly harder than oak, but will still dent with a lot of pressure. Never drag furniture or try to slide it.

Thank you Pete! We are given a Hickory - Hazelnut prefinished and priced closed to $5 / sq ft. Is this something too good to be true ?
It is and from a flooring company (not local big box) and they mentioned it is domestic American wood and comes from a local lumber.
Anything I need to watch out for and told that it comes with 50 year warranty.

The fact that this is priced similar to a Bruce Oak Gunstock..bothers me a bit.

When flooring comes with a warrantee you need to check and follow directions. Start with a flat floor. Check with a long straight-edge at least six feet, 10 would be better. Then sand high spots and build up low areas.
Good price I think. Bruce seems over-priced to me. It's all supply and demand with the market like it is, today.
Read the instructions that come with the flooring. If no instructions then look up NWFA recommendations for laying wood flooring. They have a whole pamphlet.

Pete - can you please clarify if any Prefinished hardwood be it Oak or Hickory greater than 3.25 inch in width, will it need to be glued and nailed down?

This is for the 2nd floor -
1. My installer mentioned can just nail down 6 inch wide Hickory and glue down is not necessary.
2. Called a flooring company and the sales person says "no Hickory needs to be glues and nailed-down". Is this true? This is coming from a sales person and never heard this.

3. Even if I decide to go with a 5 inch Prefinished Oak, do I need to glue down and can't just have it nailed down?

A 5 inch wide floor plank would be recommended to be glued and nailed according to NWFA installation guide lines.
You will need to consult with the manufacturer. Of course you don't need to follow the guide lines and may be successful in the long run. The glue is extra assurance that the floor will be stable. When wood wants to move because of a change in humidity it develops a lot of stress and the glue holds across the whole plank, not just one edge, like fasteners do.
The 3 and a quarter inch strip would not need to be glue assisted. It has almost twice as many fasters per square foot compared to the six inch plank.

Thank you Pete! Looks like the safest best for me is to go with a 3.25 inch or less than 5 inch.
Another option is a 4 inch Hickory but I am leaning towards Oak to have ease of maintenance.

Is Ash Hardwood a good choice? I know it is harder than red-oak but does it require more attention like Hickory floors?
Sorry for the back and forth but really appreciate the responses here. Thank you!

Both Hickory and Ash are harder than Red Oak. So is White Oak by a little. I think the cut by the mill would make the flooring more stable with changes of humidity.
Quarter sawn will be more stable in any specie. Ash is more stable dimensionally than hickory in changes of humidity. Engineered flooring is much more stable than solid, too. The goal would be to keep humidity around 50%.

Thank you for the insight. But one cannot say what kind of cut we are getting right? I thought Hardwood (3/4 inch of the actual wood) would always be more stable/stronger than Engineered as Engineered has only a small layer of the real hardwood on top of veneer or mix of plywood?

The plywood base is very stabile. The veneer has less effect of expansion and contraction with change of moisture content because it is glued to the plywood.. A change of moisture content of the veneer is held in check by the base. A change of moisture content on a 5 inch piece of solid hardwood could change the width by an eighth inch. This adds up to a lot of stress over the width of a whole room when each board can change width. Quarter sawn solid wood expands and contracts only half as much as plain sawn boards.As far as the thickness of the veneer, thin will be more stable. When you purchase flooring that is pre-finished you best get the right color so you never have to sand to bare wood. You may add another coat of finish as the factory finish wears off without sanding.