If you wish to experiment with texture, I'd do so on a much smaller canvas and try some things out. However, to do so with attention on such a large area would be nearly impossible. I wouldn't do it.

To me, the most interesting areas are the ones with the most people. The nomadic is much more interesting because it is so crowded, and on the right side of the titanic much more seems to be going on than on the left side, which is fun. The people also add a lot of color!

Another thing you could try is to give some shading to the dark panels of the ship, maybe 5 slightly different colors or so for panels in different angles or so?

To make it really interesting, there has to be something of interest on every area. And that is a massive task on something this scale. In another piece I might advice to look at the composition and just direct the eye to some kind of focus point, but that's nearly impossible here, I can't even view the whole thing at once on my screen!

I guess another part to it is: I wouldn't worry about it. It's pretty great as it is, when I see this thing I don't really have 'a lack of textures' on my mind. You've built something amazing!

There is a definite wow factor with this one because of the size and scaling accuracy.  Really impressive!   My only complaint is that there is no one saying "Jack, I'm flying!" at the front of the ship. :)

... then again ... this is a historically accurate piece.