It would depend on the color of the new tile. A boarder of smaller terracotta or travertine tiles could be a nice way to camouflage the transition. If the two floors have reddish hues to them.

6"x6" Reclaimed French Terracotta, Set of 400, Red · More Info

Tumbled Durango Cream Travertine Tile, Sample · More Info

Depending on the color of the new tile or a mosaic to pull together colors from the two different types of flooring.,

Scabos Travertine Cecilia Border, 5 Piece of Box · More Info

Or just a simple transition, with a trim tile or threshold.

1"x12" Flat Metallix Liner, Set Of 4, Antique Copper · More Info

Pictures please.

They make transition pieces in most types of flooring.

The existing tile wraps to the back (other side of stairs) to a bathroom, den and Laundry room

In an open space like that I'd keep the flooring all the same. To me it's going to look choppy to have some of the floors in one tile and the other opened floor in another tile. I'd replace it all.

Thank you. I am thinking drastic is the way to go. To much $$$ to rip up almost 2000sq ft of existing tiles.

The drastic suggestion is a good one. Wood and tile below.