I know very staid people in their 70s who've been on holiday to Costa Rica recently and had a great time. Your anxieties about it are not well-founded. But if you are as intensely risk-averse as your posts about it suggest, then Bermuda might suit you, it certainly ticks your boxes for safe, comfortable and limited.
The 'history' bit will occupy you for an afternoon. Otherwise, it is the home counties of yesteryear transplanted (and don't get me started on the environmental impact of all those lush lawns being endlessly watered with fresh water on a rock in the middle of the Atlantic). Beaches are beautiful, yes, but not better than in many many other places which are also interesting.
What about Mauritius? Not much time difference, safe and comfortable, but exotic and interesting available too for those who like it.