Looking for advice on flooring. Some details. New floor would be 26' X 22', most over existing sautillo tile with some over plywood (8' X 18') which is the new extension to an existing room. Location is south of Tucson at elevation of 3000'. This is a winter residence so it is not lived in during the summer. I want this to be a floating floor and plan on a decent underlayment also.
I am concerned about RH as it does get below 40% alot.
Questions

Bamboo or not, engineered, solid, or Cali Geowood??

What style of laminate would hold up in this environment??

Should I stick with Vinyl planking or LVP??? (Does this lock together??)

Do I need to fill existing grout lines on tile??

Will I have any issues with the two different bases (tile vs 3/4" Plywood)/

I have some time yet before I pull the trigger on windows, doors, beams etc.
Thanks in advance for your help.

Two things that jump out at me - winter home, not lived in during the summer; if this is the case, I'm also going to assume you'll be turning off the AC and HVAC when you are not at the home, which will lead to increased RH and possible greenhouse effect, none of which is good for wood or laminate products. It sounds like you'll have the best results with a vinyl installation - though keep all the blinds drawn etc, since vinyl is resistant to moisture, but not temperature, and too much direct sunlight with no AC/circulation can lead to peeling/lifting corners. Vinyl will also install better over the pre-existing tiles, which leads me to...

Two - installing over anything other than concrete or plywood/OSB or similar is typically not warranted by the manufacturer and as such, if you do choose to install over those tiles, you'll be voiding your warranty and I would not recommend doing this for future insurance or resale purposes. Countless times I've been asked this question and my answer is always the same - do it right, the right way, right now. You can't go back in time and once it's laid, you've assumed all responsibility, especially if you've done the install yourself. When it comes to installing over existing tiles, its always done in an attempt to save money, there is NO other good reason for it. Don't cheap out and save a couple hundred now only to end up with a failed install and having to spend thousands out of pocket to get it fixed or replaced later. Especially since you've already indicated that the house will be sitting vacant for long periods of time, which opens up the possibility for all kinds of things to go wrong. Get the tiles removed, prep the subfloor (you may have to replace some of those panels), and install according to all the directions recommended by the dealer and manufacturer.

Thanks for the input. It looks like vinyl is the way to go. Can you provide any guidance on costs for removing existing tile flooring??? Area is 22x18. What concerns will I have with dust?? Tile is currently on concrete slab, will that have to be ground or sanded smooth??

Cost will depend entirely on who you get to do the work, I'm in Canada and the demo can be anywhere from .50-1$ per SQFT to remove the tiles, then you need to prep the concrete, so grinding/patching, since the tile removal will take pieces of the concrete up with it. If you're lucky and the removal goes well, you can do less grinding and maybe get away with self leveller to smooth it over - your goal is a flat subfloor, not necessarily a level one (flat to 1/8th over 10ft is the ideal). If you only need self leveller, that can be done yourself, but I'd recommended any grinding be done by a professional with the proper gear and experience, to avoid any mess ups or rework. I have a couple subs I use and they charge me 1-1.50$/SQFT, which is well worth it to not have to worry about subfloor problems during and after the installation.

I have pets and we are wanting something easy to clean. what do y'all recommend? the wife is usually up late so we want something not to loud either.

Cork flooring is another choice. It comes pre-finished in 1'X3' tiles with different finishes so you will have color and grain choices. It is a floating floor that would be OK over tile if the surface was leveled with a self leveling or skim coat underlayment.

Bamboo is hardly sustainable and strsndvis full of chemicals.
It's shipped halfway across the world and is horrible in dry climates.

Considering your location and concerns about relative humidity, opting for engineered bamboo or Cali Geowood would be wise due to their stability in varying environmental conditions. Look for laminate styles with high durability ratings suitable for your winter residence, and consider vinyl planking with locking mechanisms for easy installation. Prioritize addressing potential issues arising from the two different bases, perhaps by consulting with a flooring specialist for tailored advice.