Yes, you can paint the peninsula Eider white. I would not mix tile finishes. And I'm wondering if the reason you can't choose between those two tile colours could be that the white is too white and the taupe is too dark? It's always difficult to judge from photos but I'm thinking that a colour in between those two could be your answer?

The trim color in the did joining space is yet to be decided. Everything is a blank slate at this point. I will purchase the paint samples and see how the look.

You could also take a look at SW Alabaster for the trim.

Go lighter with the backsplash and definitely remove the 4" backsplash before installing a new one. Especially with the dark cabinets you'll want to have a light BS.

Love any of these for a backsplash--interesting pattern without being busy or stealing the show from the counters. Love the exotic look of the Moroccan tiles.

Choose your trim color for the entire area BEFORE you chose a white(ish) tile for the backsplash..make sure the backsplash goes all the way down to the countertop.

Thanks for all the input. I have already removed the 4" backsplash. I will paint the trim this weekend. I think I'm just gonna go with regular white. I don't want anything with a creamy or bluefish hue just a good bright white.

I'm not a pro decorator just a DIYer but my inspiration is from this lovely kitchen. I like the color on the kitchen wall in the pic.

Blueish*

That's a beautiful kitchen. You're well on your way to achieving the same look :-)