Hi there,
Car rental in Hawaii is highly recommended specially when travelling to Maui because public transport is virtually nonexistent.
Middle of June to mid August is Hawaii's peak season so, I would advise renting a car well in advance before high seasons starts to guarantee a car as they rent out quickly.
If you are looking for a place that offers privacy too, a
condo rental in Kapulua villas in Kapulua could be a good choice for you.
The Kapulua villas spread over over one thousand acres with the West Maui Mountains looming in the background and offers a more laid back atmosphere than the tourist hotspots of Lahaina and Hana.
Hope this helps
Vacationbuddy