Hi K.,
I know you have alot of suggestions already, but I have a 4 and 2 year old as well. For the past year they have been sharing a room, now they have their own but I've had it both ways. First off, what time are they eating supper that they need a snack? My 2 year old, anytime he eats he gets a boost of energy! I usually feed lunch around 6-6:30pm. Then they can only have water the rest of the night, on occasion juice or plain white milk. Pretty sure they test you, because they know they can. I usually start around 7:30-8 on bedtime 'cool down'. I turn all the lights down low or off, turn tv down (if it's on, but usually not) and we start doing things that calm them. Talk about the day, do a puzzle, color etc. Then we start the routine, get jammies, brush teeth, read book. When it's time for bed I make sure there is a routine in bed. My daughter always has a blanket and I always say sweet dreams i love you. My 2 year old son has 2 pillow, a blanket and a raccoon and I make sure I tell him he needs to kiss me goodnight. My daughter has her routine down now, but my son is still getting into it but it's working. First time he gets out of bed I patiently bring him back get another kiss goodnight and tell him it's time for bed. 2nd, time I just tell him it's time for bed. 3rd and so on, I don't say anything at all, I just bring him back to his bed. I used to take his things away one at a time but this only got him worked up and upset. I tell you it won't work every single night, but keep with the same exact routine! Good luck to you!!