One of the things I really like about grain is the added layer of complexity it can give by adding texture to an image, though, ironically, I've never been fond of texture screens or PhotoShop noise. I suppose the film grain adds something that really acts as an integral part of the image, where post-exposure manipulations simply add something additional to the shot (sort of like the difference you get in creating guitar feedback by overloading a tube amp versus running the signal through some kind of electronic processing).
Now forgive me for getting into some technical observations that address your questions or relate to things y'all have said. For maintaining shadow detail at high speeds, Delta 3200 (D3200) and Kodak P3200 (TMZ) really are head-and-shoulders above anything else I've tried. The shadow detail of D3200 at EI 6400 is comparable to shadow detail I get from HP5+ at EI 1600 (and better than TMax 400 at that speed). [I think the TMZ has very slightly finer grain, but the tonality of Delta 3200 is much more appealing (and it's available in 120 size).]
If you're pushing a 400-speed film to 1600 or more, a high contrast scene will give you empty shadows. For boosting grain when shooting under controlled, low-contrast conditions, the slower films work fine. But if you're shooting at bars or night-time streets scenes and you want to maintain shadow detail that can be printed without drastic measures in the darkroom, though, D3200 (or TMZ) really is the film to use.
John K., toning Ilford MultiGrade IV in weak selenium toner for several minutes will provide a slight shift toward a purplish, eggplant tone. The effect is probably a little exaggerated in the scan, but it's is noticeable in the print.
Christel, I've gone back and forth about just how much I like this particular print. But, as you can see, it works well for a number of people. And I 've never really thought that -everyone- had to like all my photos. . . : )
Just for fun, here's another of my grainy faces. And no matter what others think, this one is unambiguously one of my favorites.