At some point in the next year or so we want to replace all of our downstairs flooring (1k ish sq ft). Right now it's two different kinds of tile directly on the slab. From reading this board I've heard horror stories about trying to demo tile off the slab so I'm leaning toward just covering it.

We're thinking LVP is probably the most economical route and the theoretical waterproof nature is appealing so we can put it everywhere including bathroom and kitchen.

Any thoughts or concerns about covering tile with LVP? Do we need to have the existing tile covered with self leveler or is an underlayment and thicker (7mm+) LVP sufficient to cover grout lines and minor height differences between tiles without issue?

If anyone has done this and has lessons learned or recommendations for contractors in West Houston that would be great.

"The Money Pit" radio show gets this Q all the time and a good place to write/call as well as here.
My 2-cents is only the obvious warnings to insure doors will open or can be cut/adjusted to the new finish floor level ... as well as appliances, e.g. DW has enough headroom to under counter.

Exactly 1 year ago, I had tile removed from the slab. In addition, there was original 1973 linoleum tiles under the carpeted areas in the entire house. I had it all removed, I re-carpeted the bedrooms, but everywhere else got LVP.

It was messy, but not a huge issue.

I recently did a similar replacement with LVP. I had little issues getting old tile up. Get a long-handled scraper. LVP is waterproof on the surface but water can get under the edges. I did not put it in bathroom or kitchen for that reason. I had some imperfections in my slab. LVP is pretty good at hiding. If your grout lines are thin you might be ok. Shallow areas say 6-24" will leave a gap under your LVP and will result in some give when you walk on it. Float any such areas to level out. I would recommend removing old flooring. LVP on top is going to create lots of issues with door gaps base trim etc

Difficulty of removal depends entirely on how well the tile was installed. I've had total hell (tile setter knew what he was doing / on slab) and done in half an hour because it was on a crawlspace and inadequately supported. It's just a roll of the dice.