Sleeping trouble...

Here's my problem. When it comes to getting my kids to sleep, I have NO CLUE what's normal. Landon has always been a nightmare when it comes to sleeping. Addie on the other hand has been a dream! (nightmare and dream, that's funny, since I'm talking about sleeping...) Until recently, our sleeping routine was something like this. Eat dinner, go directly to the bath. After bath it's lotion and pajamas. Then scriptures and prayers. Maybe play for a bit, then Addie is taken to her bed and laid down, while I rocked Landon to sleep. It usually only took about 5-10 minutes to get Landon to sleep, then I'd just carry him up to his bed and lay him down, by which time, Addie would be asleep, so it worked good for us (it worked good, if you don't count the IMMENSE guilt that I felt every time the perfect angel, Addie, was laid down by herself, and the adorable devil, Landon, was getting one-on-one attention and being rocked and cuddled to sleep). So, I decided last Thursday to get them to fall asleep on their own in their own beds. Since they share a room I knew this would be tricky, but I also knew it was something that needed to be done. Well, I guess my problem is, I'm not sure if I'm expecting too much from my kids at bed time, or if I need to be stricter. We have started trying to go to their bedrooms right after bath time, and then they put the pajamas on and we lay in Landon's bed while we do family scriptures and prayer. Then we give kisses and cuddle a bit, then Steven and I leave and hope the kids will go to sleep. So they're in their beds between 7:00 and 7:30. Well, it seems like as soon as we leave, all heck breaks loose. Landon and Addie start talking to each other, throwing all their blankets off, jumping on their beds, needing drinks and bathroom breaks, and who knows what else. I try to not interfere unless they're out of their beds or being really rowdy, and most nights they're asleep by about 8:30.

So, my question is this: Is this how bedtime is in most houses, or just mine because my kids are PSYCHO? Is it too much to expect them to fall asleep in about 15 minutes instead of an hour and a half? Am I just setting myself up for disappointment and failure by expecting them to remain calm children when we leave the room, instead of transforming into possessed monkeys? I'm hoping that it will get better and easier the longer we stick with it, and I am aware that it's only been 4 nights, so I don't have much to complain about. I was actually expecting it to be much worse than this at first. But I am wondering if it will get better if I keep being strict with them, or if I need to just come to grips with the fact that getting them to sleep will always take about an hour. Any advise would be helpful. Here's how Landon fell asleep tonight (after and hour and a half).