You should be able to see stuff from the beach, but it really depends on the wind direction.
If you're not going on the water, it's probably best to get there early in the morning, before people leave the beach. That will give you the opportunity to see the boats up close and talk with the sailors. Then hang around a bit after they leave and watch the races (bring a hand-held VHF if you've got one so you can listen to the race committee).
You could get there in the afternoon when they come in, but the timing is less predictable and the sailors will be focused on putting boats away and hitting the shower.
The best seats are on the water, though. If you've got a whole day to devote to it, volunteer to help with the race committee, either on the signal boat or one of the mark boats - no experience necessary! PM me if you're interested and I'll hook you up with the principal race officer