12x24. Consider other projects you might have on the horizon before making a final decision on tile.

Thanks for the comments. New carpet is on the horizon. Carpet suggestions? Any suggestions for wall color? Current color once coordinated with kitchen wallpaper which is now gone. Looking for updated fresh look!

You could have your grout dyed to a lighter color. It would lessen the definition between tiles and give the appearance of a larger tile. Much more cost effective than tearing out and replacing all that tile and it would leave you room in your budget to make any other changes you'd like. If you're replacing carpet on your stairs and in bedrooms, I'd look for something neutral. Bring home samples and see what works well with your flooring. I always like the look of a loop carpet with subtle design but in your case, I think I'd just do a very low pile since you don't want the carpet pattern to compete with your floors.

What's your favourite colour? You can pick a paint colour in that family that plays nicely with your tile. Then (before painting!), look for a carpet that will get along with both. Adjust your paint colour as needed. Just remember that if you choose a dark colour, you're going to need to add a lot of extra lighting.

John Bridge gives great advice about grout colorant.

http://www.johnbridge.com/articles/re-coloring-grout/

That being said, it is much easier and cheaper than replacing all the tiles!!!

I've seen grout recolored many times with great results for not a lot of money.

Yes, there are pros who clean and re color the grout. It is tedious (thus expensive) work for a large area, but to,lighten the grout would give your tile new life!
Make sure you find someone who really knows what they are doing.

18" tile. 12×24 is more expensive to install. Have u thought of laying a LVT or LVP over the tile? The blue walls have to go! Go with a color with warm tones in it to be safe.

Thanks Bradson Flooring for your suggestions. What is an Lvt or Lvp?

LVT-luxury vinyl tile, LVP-luxury vinyl planks.

@Bradson Flooring...over the tile? Interesting idea...Will it work without any indents over the grout?

Replacing some of the tiled areas, especially in the hallways, with hardwood would give your home a welcoming and friendly atmosphere. I would even consider running the hardwood into the kitchen to unify the space. If you were to do that, I would then paint the cabinets so you don't end up with too much wood.

If you go to a larger format tile I would suggest you run a flooring deflection calculation to be sure that your floor structure is adequate for large tiles. Otherwise you are just asking for trouble with breaking grout joints, cracked tiles, or tiles coming loose. The John bridge forum does have such a calculator on the site.

Thank you Kivi for the suggestion to make sure I don't create a bigger problem than ugly tile!

Yes over the tile. You may have to fill in the grout lines depending on how thick the LVP is. Coretec Plus has a solid body so the subfloor doesn't need to be perfect.