It really depends on your heat tolerance, particularly now, given global warming. We took the kids to Majorca a couple of years ago and found the heat pretty unbearable - 35 degrees every day, which meant we (the kids as well as us) just couldn't face the beach or pool during the day - we hid inside between about 11 and 3. The only times I really loved it were the early mornings - breakfast outside, early morning walks - and after about 5 or 6 - beach in the evening followed by dinners outside. Also, we found the landscape very arid - it's a beautiful island, but everything was so brown and parched. By contrast, we had a fabulous trip to Sicily at Easter, which was so lush and covered in flowers - great for walking and sightseeing, but not warm enough to spend hours in the pool (about 21 degrees). If I'd been there this summer when it was 48 degrees, I simply couldn't have handled it.
If you don't love the heat, how about somewhere like Madeira? It has a less seasonal climate, so it's warm all year round but never seems to be relentlessly hot (mid to high 20s in August), and is always green and flowery. Because it doesn't have many traditional sandy beaches, it doesn't attract loads of families - it's quite popular with older visitors, so it's very quiet (not the place to go for nightlife!). For your husband, there are lots of beautiful easy walks around the hillsides, more challenging walks in the central mountains, plus some interesting history, nice towns and wineries to visit, boat trips etc (we saw dolphins). The cuisine isn't the most exciting, but it's pretty straightforward (lots of grilled fish and meats). Although there aren't lots of beaches, there are still a couple of small ones, plus coastal swimming spots, and lots of nice hotels with pools. We went pre-kids, but I'd have thought it would be great for a child with sensory issues - very quiet, very easy and not too hot.