Atlantis
 

Decided to wear speedo at beach and pool, but mid-thigh shorts type suit to water park. However, after about an hour on the slides, i ripped my suit (side seam so nothing much was showing). I still didn't want to risk continuing to wear it and it would rip further with embarrassing results.
I had 2 choices:
1. Wear the speedo on the slides.
2, Buy a new suit.
I went with #1.
There were few, if any men in speedos on the slides. I did hear a few comments from other guests and one attendant said they were discouraged because the bottoms tend wear out or rip on the slides. I had no problem otherwise.
While speedos are extremely rare on the slides, while still in the minority, they are common enough at the pool and beach that I did not feel out of place. Even saw several men beside myself in them at fast food counters. While I assume they would be allowed at outdoor table service restaruants, I didn't push it that far. I didn't see any, but did see men in more conservative swimwear and women in fairly brief suits.
Seems strange to me that you had to wear a shirt or coverup over a suit just to walk from your room to the door of the building, but could go into a full service outdoor restaurant in just swimwear.