I just finished up my first dozen steelhad tubes yesterday. The most promising look to be the flies tied in the round. A pattern I have been fishing for a few years (from the pages of Wild Steelhead and Salmon magazine) called the Tippet Shrimp, is a natural for tubes. You won't need a hook keeper for this type of fly. Tie your hook on with a short perfection loop and pull the knot into the tube, this seems to secure the hook but should still allow it to pull free when a fish is hooked.
I also tied a few bunny leaches on tubes, they will need some type of hook keeper to keep them swimming upright. The tubing that my buddy gave me for hook keeper material is small diameter black rubber, it slips tight on the end of the tube and holds the hook securely but I don't like the way the fly looks with a black but. I will be looking around for somthing similar in a clear tubing.
On another related note, I didn't have a tube fly mandrel, so I took a large paper clip, clamped it in my vise with about an inch sticking straight out, then bent a kink in the middle with a pair of hemostats. The tube slips tight over the kink, seems to work fine, I tied a dozen flies this way no problem.
In looking through my boxes of hooks I came up with some Tiempco 800S size 4 saltwater hooks. They seem to be just the ticket for the flys I tied up. By the way Juro FYI it is snowing here this morning.