I'd probably also go with spline IK if this is going to be baked to a joint system. Is it important to retain the volume or is this magically überstretchy? Will is shoot out quickly against a target or move slowly? Move more straight or wiggly? Fill us in on how you intend to animate this.
There is the membership tool for clusters and other deformers. Go to edit deformers -> paint cluster weight tool and paint the influence of the respective cluster to the mesh. With that you have full control of clusters deformation. Also on a side note: for stuff like tentacles I also find ik spline handles very useful,…