Okay, personally I find it ridiculous that you were told to come back at a later time just because a parent-baby class was going on. Honestly, I wouldn't want to get in the pool anyway with that much irritation and noise all around me, but still you have as much right to be there as anyone else. That activity was probably taking place in the shallow end of the pool anyway, why was it not allowed for you to simply swim in the deep end?
Anyway, I'm done ranting about that now.
Another place I would say I hate to see little infants, babies and toddlers is in the more adult themed Amusement parks. I can handle the lines because I love thrill rides but what turns waiting in line from boring to irritating is when you have a mother who insists on taking her kids on the ride with her.
First of all, usually the family is somewhere right in front of where I'm standing in the line and the kids are usually noisy, fighting with one another or they are just plain rude. Then when you finally make your way up to the entrance to the actual ride, the mother seems to be oblivious to the fact that adult-themed rides have a height limit. So then the whole line stands there for an additional ten minutes on top of waiting in the line while she must measure each child against the scale and convince the ride operator of why she should be allowed to hold the child in her lap so she can get on.
Then, she either gets mad when she can't get on and storms back through the crowded line with noisy children in tow, or she gets on the ride (after rounding up her 1 to 3 kids) and then the children begin crying because now they are scared or didn't really want to do it to begin with.
Seriously, it almost ruins going on the ride for everyone else. Going to an adult theme park with children kind of defeats the purpose of going at all, considering the point is to get away from things that cause you stress. People with kids should take them to the resorts that are more aimed toward little kids or just leave them with a babysitter for the day.