I think there has been some awesome advice in this thread

The only thing that concerns me, is this statement.....
"I think one of these large animals would be perfect for the center of my tank, right between the two islands and at the entrance to my rock wall cave."
Any anemone will live, exactly where IT wants to. They aren't like a coral that you can glue down. My tank is a mixed reef, and I rearranged my entire tank, flow, and rockwork, to make the haddoni (which hosts 2 picassos btw) the "perfect" spot, that I wanted it to host. It stayed there for 2 months, and has since decided it wants to live right next to the LTA. My clowns play in both

Neither one of which they are supposed to like lmao
Point being, what is your tank like? Are you going to stress if the gigantea nem decides it likes being up on your rocks on the right side because you have more flow there? Or because you love LPS and you have it on your sand bed that your haddoni bulldozes?
Or better yet (what happened to me!) I planned on a gigantea, and got a haddoni (it can be hard to tell them apart when they are stressed and in the fish store. And it's my understanding that many suppliers don't do a great job of differentiating. I ordered my nem as a gigantea, when it arrived, I had doubts, but, it was blue, gorgeous and healthy, so I took it, knowing it was likely a haddoni) So I had to modify the flow, the rock I wanted it to live by, etc.
Carpets aren't for the light hearted, or control freaks lol
Oh, and FWIW, the LTA hasn't moved in the 2 years I've had it.