The medallion tiles can have a different grout line than the field tiles. Don't use tarpaper. Use a crack resistant substrate such as Ditra.

I hope you meant thinset and not mastic. You will also need to ensure that your floor is strong enough or take measures to strengthen the floor. Hardieboard and other cement boards to not add structural strenth and your installation will still crack if the floor is bouncy under the cement board.

By old wood subflor - do you mean plywood or do you mean 2x12's laid diagonally? If the latter, your floor is highly unlikely to be stable enough to support tile. That type of construction, while fine for many types of flooring, is generally not suitable for tile. When you walk across the floor, do you notice any bounce? What is the support system under the subfloor?

Yes, I meant thinset. I have 3/4 inch fir boards over the joists for a sub floor and it is a little bouncy. Would adding 1/4 inch lauan stiffen the floor enough? Then thinset, hardiebacker, thinset? I hate to raise the level up too much above the living room floor.

You will need a minimum of 1/2" BC grade plywood and then top that Ditra or 1/4" CBU layed in thinset. Depending on the joisting, span, and on OC spacing I might go with with a thicker plywood. Never put luan under tile either.

Rule number one... any bounce or flex spells death to a tile installation.

Thanks for the advice. The entry is small--4 feet by 7 feet. The floor joists run in the long direction. I will use a heavier plywood, and just work on an elegant transition down to the living room.

Cakie