I am in the process of printing (hybrid) some 35mm slides (KR64 and Fuji Sensia). On screen the scans differ a lot in color (I prefer much more film) compared to digital (which I use in a more careless way, BTW; Only JPG). For me a 8x12" print is quite big at the moment and medium speed film should fulfill nicely. Some grain doesn't hurt and it can help in acutance.
Slide needs a careful approach to (hybrid) printing, as I found it loses "crunch" (transmittive to reflective media).

I've gotten some Portra 400 to try and want to get a bit of ektar for next spring. As of products, Portra 400 has lots of praise for what it delivers, being ISO 400. I wouldn't be surprised if it's grain wise on par or slightly grainier than Kodachrome 64, at 8x12".