[Sylvanfan]

Well usually tiles are about 3/8 thick and than with the thinset mortar you're adding about another 1/16-1/8 of an inch. So with a 1/4 piece of plywood on top of your subfloor plus the tile and mortar should make the tile floor approximately 3/4 high which should match up with 3/4 hardwood planks. At worst you'll have a 1/8 gap which isn't really noticable, especially if you have a decent piece of metail edging where the tile and hardwood meet up.

My floor has a goofy 5/16 plywood on top of the OSB, but the tile and hardwood match up perfectly. Although my wood floor is 11/16" instead of the usual 3/4". But I don't think my tiles where 3/8 thick either, more like 1/4".

I also reccommend using a number system on your baseboard if you're going to re-use the existing baseboard. ie write the number on the wall and on the back of the baseboard with a sharpie. Even if you're using new baseboard it's not a bad idea as you can use the existing piece as a cutting template.