I'm the OP. We just returned from visiting a couple more flooring stores (we've now visited four flooring stores in total). One place today was absolutely excellent as far as having a long-time salesperson/owner who really knows her products and their uses in various applications. In a situation like ours she highly recommends using luxury vinyl sheet with a glue down installation. It will adapt to minor dips in the floor, it is all vinyl so could withstand possible water incursion, it won't have potential dirt in the edges like tiles would if there is a water event in the basement, it is durable (she showed us some great examples of what can be done to it without harming it), and it is reasonably priced (not cheap but not as pricey as many other options we've seen). I liked what I saw in the Mannington line wood-replicas because it is not cheesy looking, and it has an aluminum oxide coating to prevent damage to the floor. This floor would cost about 50% of what a marmoleum floor would cost us. Hope this helps anyone else who is facing the same dilemma we are facing about flooring.

My son and husband have severe allergies so carpet is not an option but thanks for the suggestion. I really would like to go with the vinyl plank flooring and have began my brand research but was hopeful someone had already been done this road and could offer some advice on safest/healthiest options.

I do not like tile in a basement because it is SUPER COLD. In HOT climates (not even warm....but HOT) this is tolerable/accepted. If you wish to turn this into a legal (or illegal...your choice) suite, then you will want to think about sound. Carpet is deadening the sound moving between the upstairs and the down stairs. Before you go ahead and pick anything, you will want to take note of how the carpet is deadening the sound right now. Then pull out the carpet and leave the cement exposed for 2-3 weeks. See how much of a difference a sound deadening property the carpet offers. There are a few things that will recreate that deadening: 1. More carpet 2. Cork floating floor with cork underlayment 3. Laminate with sound deadening underlayment 4. Subfloor system (like Patricia's) like Dricore with vinyl over top Vinyl does NOT like underpad. That's where it gets tricky to reduce noise with vinyl. Laminate is different, it LOVES a good acoustic underpad. Just a little bit to think about before you convert the basement to an apartment. You might find you have to update the noise insulation between the floors before you rent it out.

Moisture/vapour barrier is ALWAYS a warranty requirement for any floating floor in a basement. An older slab will have moisture issues (anything from the late 1980's to early 1990's or OLDER). And the NEW slabs, that have the moisture barrier underneath, are always considered to be 'damp' (ie. a rock pierced the plastic, or a tree root, or the contractor didn't lay the plastic properly or do the seams properly...that sort of thing). That's why all floating flooring warranties REQUIRE vapour barrier. I'm not sure why this is missed so often by Contractors. Mind you, a good flooring pro will know this, a General Contractor may not.