Liveaboards are the way to go if you are primarily concerned about diving. Its my preferred means, I can get 4 dives a day at great dive sites. Its actually the only time I'm ever eager to wake up early to get the early morning dive, especially true if its a dive site that day trippers can get to. You can get out of the water before the cattle boats arrive. I've also only have had positive experiences meeting new dive friends on boats, sharing stories and beers at the end of the day.
However, not everyone wants to only dive. If you were land based in Thailand, you could still enjoy the beaches, night life (who doesn't like a good beach bar?), spas, other land based activities. And if you are seasick prone, you will at the least know that you will be on firm ground before nightfall and could change your next day plans.