Floors and flooring:
Concrete slabs are pretty darn maintenance free
IF they don't crack and if you don't have a water pipe break underneath them. You can avoid the first problem by hiring a really good contractor to do your slab, and ensuring he preps the lot correctly, uses high quality concrete, and uses appropriate steel reinforcement.
Basements: I like my basement, but if I were building from scratch I don't know if I'd have one. The conventional argument is that (in much of the country) you have to dig down at least 3 feet to get below the frost line, so you might as well dig farther down and get another level for "free." In truth, it's far from free (moving dirt costs a lot of money, and you still have to build walls, just like you would above grade). And what do you get at the end of the process? Some living area that is dark and possibly prone to flooding/condensation of the walls, etc. There are "new" methods to build directly on a slab with a thickened edge and have no problems with frost heave even in very cold areas. It's done by insulating the ground outward from the home using buried "wings" of rigid insulation. The natural heat from the ground warms the ground under the house and keeps it from freezing. The technique has been used in Scandinavia for many, many decades and it works great. It also saves money during construction. If you want the added square feet offered by a basement, it is cheaper to build it above grade. For more info, see
the oikos site for a start. Based on what you've said, I think you'll like a lot of the ideas at that site.
Flooring: The acid-dyed concrete floors look great to my eye, but they do require re-sealing every few years. You might like cork. It's natural and renewable (though most of the flooring does contain artificial binders/glue), it feels really good underfoot, and it is fairly durable. I know vinyl has a bad reputation, but I like very much the high-quality sheet vinyl floor in my kitchen and bathrooms. No grout to clean, wipes up easily, doesn't break my dishes when I drop them, and it wears well. I think you are smart to avoid wall-to-wall carpet. I like our real hardwood floors. A few throw-rugs (pick them small enough to wash at home and you'll do it more often) for the spots where your bare feet demand it.