The quilt I am working with has a large(size of a queen size bed top less pillow space) medallion in it . out side the medallion are 2 rows of wide sashing (the drop) I guess, I could set my machine on its longest stitch and 'baste' an x and a + to stabilize it , then go to the middle of the 9 patch medallion and begin. Does this seem reasonable?

I have done many that size. I used basting spray and started from the middle out. And I basted around the outside edge because if I had any problems thats where they were. Good luck and have fun.

You have to baste the entire quilt well before you ever begin quilting, so adding an additional basting "x" seems unnecessary.

The "x" i described applies to most machine quilting patterns. However, if you are planning to machine quilt starting at the center because of the medallion motif, then what I described no longer applies. The whole purpose of starting at a middle edge rather than in the middle of the quilt is so you don't have to worry about hiding your stops and starts.

With a medallion, you will have to figure out how to hide your stops and starts since you will be starting in the center of the entire quilt. This is unnecessary if you are machine quilting cross-hatching, or an all-over stipple, or any other pattern that includes borders; in that case, you can still work from the middle out, but it should be from a middle edge to another middle edge.

This is harder to explain than to do!

There was a recent thread about this method. Here is the link to that thread:
http://www.quiltingboard.com/t-38246-1.htm

Now here's an interesting idea.

Think I'll wait for someone else to try it first, so now am eagerly awaiting feedback.

This had worked for me as well.