I suppose a lot of places could be tried, and some can be somewhat 'rustic' if you desire. Since we're a diving forum, I'd work with that.
Have you been to Bonaire? It's not as densely populated as Aruba, shore diving lets you go at your own pace without dealing with charter boats (unless you want to), and you can take a day to cruise through Washington-Slagbaai Park for scenic views and photography, drive through the donkey sanctuary, and if you're really adventurous give kite boarding or wind surfing a try. You'll see other dive trucks out, but it's got a rustic feel to it, and there are restaurants to check out if you like.
Some resorts would be more 'serene' than others. I like a resort with a nice house reef for on-site diving at well, personally, though I enjoyed the cost savings at Dive Hut.
I've never been to Saba, and it'd be charter boat diving, but from what I understand it's pretty rustic.
Richard.