Very close to Lahaina, just as you're headed out of town traveling south is Puamana Beach Park. Puamana is small beach park with picnic tables and lots of shade. It is a good spot for beginning surfers and during a swell usually breaks from a southerly direction. Sometimes a large northwest swell will break very nicely here as well, but this spot is more consistent in the summertime.
The waves break right near the shore, so you don't have to paddle too far. It is a perfect wave for longboarding as waves are mostly gentle and usually range from 1 to 3 feet. Views of Lana'i, and sometimes the western, flat and dry side of Molokai are visible from Puamana Beach.
If you can see Molokai pretty well, then look even harder. On the very clearest of days, you can barely make out the island of Oahu. Puamana Beach Park has freshwater showers. There will be no sand on the beach unless there haven’t been any south swells for quite a long time giving the sand a chance to return. There may be some lovely sunsets to be seen from this spot since it sets behind Molokai and Lana'i.