Sedum love our PNW growing conditions and they have never become invasive here. They tend to be very shallow rooted and are easily removed if they start growing where you don't want them.
That said, my Sedum 'Blue Spruce' set seed everywhere in a semp bed that I planted a small new plant 3 years ago. Last summer I removed it because it was getting to big for the raised bed. It is a lovely plant and I have it growing elsewhere in the yard. A very carefree plant. If you don't want seedlings, just remove the bloom stalks once it is finished blooming, before seed is matured. This one will stay shorter if grown in pour soil, no fertilizer, and not much water.
