Hi,
Thanks for giving us a background, I'll switch gear then
-- Database or xml if the way to go, Xml will give you a quicker overview and faster editing/ease because it's all plain text and plain english. DataBase will scale better if you have REALLY big levels and expectations.
https://www.assetstore.unity3d.com/#/content/4334Database: use one of the asset store kit that will give you access to sqlite, some have playmaker support, so you are covered.
Xml. I have a pending framework in my drawer, that will soon be released on the user wiki, pm me, and I'll share it with you. It will give you raw power to perform xpath queries and extract anything from our xml, and it's very efficient.
Now, that part covers your "assets" that you will want to randomize, in terms of implementation IN your game, you will likely have to define the various places where you expect randomization. If you want the level to have different walls placement and all, then that randomization will have to be as a first pass, not as an on going ( tho it's possible, but likely giving more trouble to implement).
Could you elaborate on what you want to randomize? I'll then be able to point you in few directions for practical implementation.
Bye,
Jean