We expect our stallion and colts to act like any other horse - mannered and responsive.
Our old TB stallion (we lost him a few weeks ago) was my 3 y/o daughter's "pet" - that horse would follow her around like a puppy dog waiting for her to stop for him to get pets & kisses. It was never a 2nd thought to throw her up on him for a leadline ride. But he knew that if a lead rope was on him that his attention was on his handler no matter what was going on around him. He knew the difference between work time and breeding time. But even given that we never forgot that he was a stallion and that meant that we made sure that we were always aware of what horses were around us. Funny how Stallions can get the bad rap at events, when it is the mare's handlers/riders/owners that should have had the better handle on their mare from being too close to a stallion when she is coming in season. In his youth our guy was trained for the race-track, injuried in training, recouped at his owners farm, retrained and barrel raced before being "forgotten about" for years. But all the old stories I heard about him from locals who knew him in those days - he was always treated like he was a gelding and never allowed to not behave, we just continued that thought pattern when we had him.
That being said. We are currently raising his 2 y/o son to "hopefully" be his replacement. He is obvioulsy not pastured with our mare's (4 open mares this year), but has an older gelding pastured with him - who also happens to be my pony horse when I'm schooling the babies, so he knows that the gelding wont take any flack from him. He gets the same handling as any other 2 y.o. - beyond making sure I don't pasture him with the mares. Right now he is about to head off for 30 days under saddle of "real work" to see what he "wants to be when he grows up".
On gelding "late" the saying that a "nice stallion" always makes a "wonderful gelding" is always true. Sometimes it take a little while for the hormones to settle down after gelding, especially a stallion that had been used for breeding. My old gelding is 18 years old this year - he was gelding at 8, after being used for 3 seasons at stud. He still has attitude days, but he had attitude days before he was gelded. Personally - unless there is a real REASON for keeping a colt intact (bloodlines, disposition, etc) and a market for his foals come that day. Then the best life for a colt is that as a gelding. We gelded all except this one colt - and there was just something about him from day one that set him apart that we want to give him a chance to prove himself undersaddle before we decide to leave him intact or geld him ~ but he wont be bred until he has proven himself under saddle.