I found NCA a magnificent park. Unique scenary, wild animals basically everywhere and easily to spot and see while they e.g. move, drink from the lake, hunt, rest.
1/2 days in ngorongoro is in my opinion enough as the crater is not that big. Accomodation is somewhat expensive and one may consider staying in one of the villages just outisde the NCA for good accomodation at molre reasonable prices. A trek on the Empakai crater possibly walking , guided by a masai, as far as lake natron is an amazing experience.