Probably a better idea with the 128D, that way the keyboard is essentially done, and like you said there isn't a seperate floppy controller board to deal with.
I just got my 1541-III (ordered a pre-made one from Jusi so I can play until I build one for myself). You can control it without an LCD so that may be a nice option as a device 9 (or 10 or 11) in a tower.