Not sure I understand the question, but I'll try to answer what I think you want to know:

I would never want to go from the airport (arrival, tired etc.) directly to the beach instead of first going to my hotel and even less want to go directly to the airport from the beach (full or sand and salt water etc. - there are showers, but still!) If others are not like me, I do not think it is very convenient transport wise. It is not like Amanusa is on the direct way to the airport from Amankila or Amandari. It is close, but still like 30 minutes away from the airport (often heavy traffic, too).

Combining Amanusa with excursions is also not ideal as there is really nothing special to see in that direction. There is Uluwatu temple (40 minutes south of Amanusa by car, but other temples are nicer), there are some shopping malls not too far away from Amanusa (but not interesting enough for an excursion I would say).

Rather, if you stay at Amanusa or Amandari, it might be interesting to visit east Bali as an excursion with stop at Amankila, or if you stay at Amankila or Amanusa you might want to visit Ubud with lunch at Amandari.