I just bought a home and want to replace the worn out carpet with hardwood in the dinning room, family room, and hallway.

The house is on a slab foundation. I have two questions:

1. I was leaning towards a natural hickory as I like the way it looks and it is harder than maple, so I figured it would be durable. I also know that based on what I have read that I should stick with engineered since I am on a above ground slab. That said I live in a dry but moderate climate, near Sacramento CA. Will I have trouble with Hickory? I ask because I have seen a few comments in the forum warning that hickory can be an issue in dry environments. If I should avoid it what alternative would you suggest that's more tolerant to a dryer environment? I do prefer the lighter colors but not a fan of the bamboo.

2. Also being that it is the middle or late summer and it hasn't rained for a few months now do I need to worry about checking the slab for moisture? I plan to use a vapor barrier as recommended. part 2 to the question: Are the combination pad and vapor barriers ok or should I use a separate vapor barrier even if the pad has one built in?
On that note I know that I need to do some work to the yard (before the rains come) to ensure that there's proper drainage and I have ever intention to ensure that water is shed around and away from the house to prevent moisture build up.

Any wood can have some issues in a dry environment. The thing to do is buy a thermohygrometer alike at Radio Shack and keep tabs on your interior rh. Wood moves because of moisture and it drys out and checks due to the lack of it.

If you can control your interior with HVAC and a humidifer for dry times you'll be fine.

All slabs should be checked and grading with gutters helps immensely. Vapor retarders like the 2 an 1 combo type are kinda weak, least most of the ones offered at box stores, there are better ones out there. But if you want to double up your protection (and it is advised if emission rates or rh in the slab is high) Put six mil under the combo mat. I could go on but thats the basics

Thanks for the feedback!

So does that mean I need to keep the rh between 40 and 60? I hate to think I can't open the windows in the evening or have to leave the HVAC on all day long or while gone on vacation? Currently the rh here is in the mid to low 20s and in the winter the rh can get towards the mid to low 80s. Just wondering if Hickory isn't advisable and if not should I go with Maple or some other solution.

I highly doubt that the emission rates or rh in the slab are high at this time of the year. Assuming it is low now I am just concerned that could change during the winter and want to error on the safe side. I wasn't sure if doubling up was a good idea or just overkill.

You'll be safe with engineered hickory. Just make sure it's installed at the "median" rh for your area.

Thanks for the feedback.