I've not been to Maui in July but have sucessfully nonreved to Honolulu in mid-late July without any trouble.

There are a number of properties that offer interline discounts. Check out the following.

www.ohanahotels.com
www.outrigger.com
www.astonhotels.com

Ohana and Outrigger offer online booking for nonrevs. Just tick "Travel Industry Rates" on the booking page. Once you've chosen a property you'll have to call Aston for their interline rates.

Hope this helps!