They do start very handsome and get to be quite impressive after a few years. I've had a few nice specimens over the years but always ended up messing up and killing them. They don't like temperatures much below 6°C when they're younger - and the one I nurtured to an appreciable size got damaged and succumbed to galloping rot.

Trichocereus keys are plagued by the variability and interbreeding of the species to some extent. Nonetheless, I would point you in the direction of the works of Keeper Trout, and Patrick Noll for the flowering hybrids. There should be a link to K. Trout's "Sacred Cacti" somewhere in this thread.