February Safari/Beach itinerary advice

My wife and I (mid 60s) are in the midst of planning our bucket list safari/beach adventure for Tanzania in February. I've made contact with a number of TOs, and through insights I've learned on this board, I'm trying to tweak our "ideal" itinerary so that I can compare apples to apples proposals from 2-3 operators. I would love to get feedback an suggestions on our itinerary/accommodations as they are described below. Naturally in February, our main objective will be to witness the calving season in Ndutu and we would also like to see big cats -- one of the TOs suggested central/eastern Serengeti for this purpose. As much as possible, we are trying to spend multiple days in one location to avoid the hassle of changing locations every day or two. The exception here is that we will be staying one night on the Ngorongoro rim, but because of the way we are approaching it we will descend into the crater twice, first in the afternoon and the next day in the morning. Accommodations as indicated below I believe would be considered "mid-range" rather than luxury. We are trying to keep our budget below $10K per person (lower of course would be better). As it stands, our 15 day trip looks something like this: Day 1: Arrive and overnight in Arusha Day 2: Travel to Ngorongoro Crater, afternoon game drive, overnight on crater rim (Accommodation: Lion's Paw) Day 3: Morning game drive Ngorongoro, Travel to Ndutu 3 nights (Accommodation: Masek Tented Lodge) Day 4: Ndutu Day 5: Ndutu Day 6: Check out Masek travel to Central/Eastern Serengeti, spend 3 nights (Accommodation: Nyumbani Collection) Da7 7: Central/Eastern Serengeti Day 8: Central/Eastern Serengeti Day 9: Check Out Nyumbani Collection Fly Zanzibar spend 7 nights (Accommodation: Pongwe Beach Hotel) Day 15: Depart Zanzibar Overall, I kind of like the look of the itinerary, as it appears to provide ample time at each location that should help in providing an unrushed safari experience--but I still have a few questions: 1. Is 7 days on safari as laid out above sufficient to give a full safari experience? As it stands now we are spending 7 days on safari and 7 days on the beach. This is by design as in our hearts we are truly beach lovers. Yet, at the same time I wonder if we are spending enough days on safari. For us, we are only going to be able to experience the tremendous wildlife in east Africa once. I realize everyone has different preferences, but just curious, how might you split your time between beach and safari? 2. In our initial itinerary planning we were considering a tour of Tarangire National Park for a day or two. However, I had read somewhere that February might not be the best time to visit this park. Is this accurate? Is it worth trying to adjust our itinerary in include Tarangire--perhaps by cutting adding a day to the trip and cutting a day from the beach leg? 3. Accommodations. Love to get thoughts on accommodations that we are being considered in each location: Ngorongoro Crater--Lion's Paw has been suggested by a number of TOs. How would this compare to Serena Ngorongoro safari lodge? Ndutu: Current plans are for Masek Tented Camp--any other lodges in this region we should explore? Central/East Serengeti: Nyumbani Collection. Any other lodges/camps we should consider in this area? Is the Karibu Sametu camp in this region (just a camp I had come across in some of the initial planning that I kind of liked the looks of...) Thanks for reading this far--I truly appreciate any guidance or insights you can provide!