My eldest two have shared a room and/or bed since DD1 was 2 and DD2 1. They originally each had a single bed in the same room. Then we moved house and at the age of 19months for DD2 and 2.5 odd for DD1 they began sharing a queen size bed. It started becuase they wanted to share a room. The bed sharing started because we were doing renos and it was convenient for them to share a bed, then they loved it and they stayed that way. About 6 months ago they wanted their own bed, but to still share a room. They each have a queen size bed and on weekends (ie non school nights) they will still bed share.

How to stop the games at bed time? That's a tricky one. Sharing a room started when they were just babies so I was in there with them until they went to sleep anyway - I would lie in one bed with one and DH in the other. Now they're at school they're usually pretty tired on school nights anyway and we have a pretty good routine so they're usually good. Some nights are a problem so usually that just means either DH or I have to go in there a few times to get them to calm down. Non-school nights we give them a bit more leeway, and that can get out of hand but we let them go for a bit and then start going in again. It is a downside to room and/or bed sharing, but I think the positives outweigh the negatives.

They don't wake each other up during the night but they are both really deep sleepers - not sure if that is partly due to them sharing or not.