Prior to the development of engineered hardwood flooring, hardwood flooring products could NOT be installed on slab or in your basement without a special subfloor system. Now you can enjoy real hardwood flooring in those areas without all that fuss and expense. A special cross-ply construction eliminates the problem of expansion and contraction usually associated with solid hardwood.
Engineered hardwood flooring is wood, not a laminate. There is often much confusion over "engineered" and "hardwood" products. Some believe that "hardwood" means "solid wood" and that "engineered" means imitation or laminate. However, they are the same: they're both hardwood, albeit in different forms. The geographical area in which the wood is to be installed dictates which product will serve you best. Engineered hardwood flooring products will offer far less problems in areas with high levels of humidity than will solid hardwood flooring.
Don't become overly concerned with thinner or thicker top wood layers associated with engineered products. It's the finish you are walking on. And it's the finish that is under warranty (along with the milling and structural integrity of the layers). The days of having to refinish your hardwood floors are gone. The only reason you should ever need to refinish your hardwood floor is if you want to change the color. Otherwise, you can simply screen and re-coat them -- a quick and easy process that requires no sanding.