Regarding the grout, if you're doing a grout color that is in line with the color(s) in the tile it shouldn't look too busy in any size. I saw a stunning photo the other day of a pretty busy granite, light splash tiles and super dark grout so it doesn't all have to be super muted to blend. As for what the lady said, if you love the 6x6 more than the others, do it. I have short splash on both walls of my kitchen due to cabs and a window so 6x6 would never work but I like the looks of them and didn't realize it was a trend, but what do I know? It's not like squares are some fancy new, trendy shape. ;) Maybe someone else will have better advice on that. Here is a link below. Here is a link that might be useful: Mostly 6x6 backsplash tiles

We did our whole basement a few months back in luxury vinyl tile (that's the lvt above :) ) and just love it. I think it's a no-brainer if you have dogs that will scratch up hardwood or need waterproofing (we put it through our laundry area and mudroom). On a main floor, I'd still do hardwood, because all of the other options feel fake underfoot (barefoot). But if that's not an option, the lvt is warm, soft, and has some awesome looks these days. I really think it's going to completely replace laminate pretty quickly.

Your location and your preference will dictate what is a better option. People in cold weather areas rarely like to have an entire level finished in tiles whereas people who live in hot climates want the cool feel of tile to help reduce the heat in their home. Demographics also play a role. If you are someone who lives with pain (back, neck, joint, etc) then tile can be very difficult to handle. Hardwood is easier on the body for most people. Then there is the noise issue. Tile is noisy. It allows for a terrific echo in a space. If it is the entire downstairs then the noise from conversations, TV's, speakers, etc will simply bounce down the hallway and into other rooms. The noise will sneak under doorways and ricochet around in bathrooms. If you have a ceiling that is a higher than 8ft, then you will have created the most impressive echo machine. And if you have walls of windows, that will increase the mount of rebounding noise. Hard surfaces (like tile, sheet rock and glass) allow sound to hang around much longer than soft(er) surfaces. A wood floor surface will reduce some of the noise created. Not all...but some.

If the kitchen flooring is next to any type of wood floor I would go for a non-wood look for the LVT. Rule of thumb is not to install natural wood next to imitation, BUT if you find a wood look LVT that works with your area and the way your daily lives function then by all means you do what BEST FITS YOU. Good luck with your selections!