My tile and hardwood are both at 3/4 height. At some areas, the wood will run parallel to the tile. So there is no way to put a transition to allow expansion. I don't really want a "transition" either.

The flooring is 5" white oak (exp coefficient 0.00365). The boards are all rift/quartered. Will I need to put a gap at these areas due to wood expansion? I was told/researched R/Q expands in thickness, not width. As far as along the grain, I don't think wood really expands - otherwise our houses would get 1" taller every summer.

It would be good to leave a gap to allow for minimal expansion. Try leaving one that will mimic the size of the grout line. Then fill it with color matching caulk.

Acrylic caulk? Silicone? I suppose the type doesn't matter?...however, I have a Schluter metal edging strip at the border of the tile so I think that might look strange.

http://www.schluter.com/2171.aspx

The tile is on a layer of Ditra which allows the tile to slide a bit but the underlying thinset is locked to the subfloor. Maybe I will order a movement profile:

http://www.schluter.com/141.aspx

If I do that it might look okay with two metal strips adjacent to each other. Wish I knew I needed this prior to putting in the tile. I would have just put in a movement joint.

I was referring to acrylic color match caulk. It can be purchased where the grout was purchased. Having a metal strip there does change things a bit.