A silly decorating dilema with tile in two rooms

Is there a rule of thumb when putting tile down next to another room with tile? I have just built a utility room in my garage and want to add tile to the concrete base. The utility room opens into the Kitchen through a door which has a metal threshold. The same tile in the kitchen is not available. I'm going to use something different in the utitlity room. Only when the door is open will you notice a different tile and tile size. I was thinking of removing the threshold and putting down a border, but was scared I might be opening a can of worms I should keep shut, if the removal creates other problems with the door frame since it appears to be built around the metal threshold. Is it a common practice to remove the threshold and put down some kind of border where the threshold was to make the transition better? That door is no longer the door to the garage (I put in another) Or since it's a seperate room should I keep the threshold and hope no one notices the difference when the door is open? Sorry if this seems like a silly question but my wife and I are about to kill each other and we could use a fresh perspective.

 

Personally I'd leave the threshold in place, from the sounds of it, I'd say it's gonna be alot more trouble than it's worth to try & remove it with unwanted damage to the door frame and as you said you only notice the difference in tile when the door is open. I'd say this is a matter of personal taste so get back in the ring & convince her that the threshold needs to stay put.