As long as the bus is going to where you want to go and you do not mind waiting for the bus, it should not be a problem.
Best to take a taxi to the hotel from the airport though. It is quite a hike from the airport terminal out to the main road. If you have bus transfers included that is fine, the only downside is stopping at each resort for drop offs between the airport and your final destination.
Taking a taxi also means you will arrive before the bus gets to your resort with a whole bunch of other folks wanted to checking in the same time as you.
Yes, do get a car if for only a day. Its fun to ride around, check out the island, see the desert, california lighthouse, beaches, million $ homes in Tierra del sol, hit flying fishbone restuarant....all can be done in 1 day....