Onegai Teacher and Onegai Twins each had some sunny outings at the beach, as I recall. Love Hina also had an episode featuring some hilariously disastrous theater productions down at some kind of beach house, though I seem to recall most of that was done at night.
Oh, and don't forget Haruhi Suzumiya. They go to the beach once in the first season (I think it's around episode 8-ish?) and then there's the Endless Eight in the second season, but no beach. Just the pool and the sun.