Complete disclosure - I won't be doing it myself due to health probs . Anyway plan on having bout 1,100 sqft of engineered hardwood over concrete slab. Glue down or float? Trust info here over than sales people -Thanks evy1

I'd go with floating. Just make sure you get a good quality floor in the $3 to $4 per SF range and use a pad designed for use as a pad and vapor barrier over concrete (about 50 cents SF).

Floating floor install will be MUCH less expensive. On glue down on top of concrete, there is always the chance of floor pops in the future unless the concrete is perfectly level.

Thanks Jaybee - but after re-searching more and with good arguements on both sides - and that this is a new and (somewhat)an upscaled neighborhood and house I'm leaning towards glue down mainly for the solid sound. I've layed laminate in lower level of different home and never liked the "hollow" sound on it or other floating floors.

my house has glued down engineered floor as was recomended by the mfgr. I suggest that you do what your manufacturer suggests
Glue down is permenent and more difficult to replace a damaged section, floating, if over a good underlayment, makes repair easy and would probably not have the hollow sound. Also, floating floors underlayment will act as a sound suppressor

This will all depend on the skill of your installer, the condition of your slab and how those two get along.

If you slab is level within the specs of the floor, then the job will be so much easier and better. Otherwise, don't skip the step to level the floor first.