Solid Hardwood, Engineered and Laminate Flooring - thrashing with thresholds

Now that I have laid the floor, I am wondering how to lay the threshold, I see that my edges that were cut, although square, because the building does not have a right angle in the house, looks jagged. How to put in a threshold, yet cover those edges and have it look nice...

I have no problem finding an oak or walnut board and cut it to fit as a threshold and bevel the edges if needed, for certain on the tile side, but it will not cover the jagged edges of the cut wood. Any ideas?

I realize I should have figured this out before I started!

See pictures here: http://home.comcast.net/~devidasvarga/cross.htm

Well, you are correct that this should have been adressed earlier in the installation, but too late for that now.
Two options. If the tile is higer than the new wood by at least 1/2 inch, you could use a wide reducer. Reducer would be width from tile to just over shortest board, looks like about 3-4". Put a filler piece in the gap and install the wide reducer over that - not ideal. but might work. You might have to make the reducer, as you suggested. You'll have to play a little where you didn't undercut the jams.
A better method is to cut the jagged line square. Use a circular saw (with a straight edge guide) and chisel the last boards you can't reach. then lay flooring perpendicular to the new flooring.. You might still need a reducer to the tile on top of this, but it could be narrower.