We have a Burley Bee. It was $200 on sale at a local bike shop last year.
It can be set up to haul one kid or two. It has a pocket for a drink/toy for the kid, and a huge amount of space in the 'trunk' for cargo (diaper bag, food, etc). For storage of the trailer itself, It folds down fairly flat and the wheels are super easy to remove.

The hitch that connects to the bike is easy to install and small enough that I just leave it on most of the time.
We put our 20 month old daughter in there with snacks, toys and books, and she is good to go. She spends most of the time looking out the tinted windows. It also has a rain cover we use when it starts raining. It is connected to the trailer and rolls up/ties down so you will never forget it.

The one and only downside to this trailer is that the seat doesn't recline, but as she is a small kid, she falls asleep anyway! Naps happen on every ride.

If I had to re-buy it, I would.