Either of those trailers would be excellent.
I would not worry so much about the fabric but don't let the trailer sit out in the weather for months.
I think Burley has improved their fabric over the years to where they are more durable than they were.
If you want your kids to wear helmets in the trailer, then look for the trailer that has a helmet pocket. This will help stop the seat back from pushing the helmet and childs head forward.
Suspension systems are nice but I don't think they are worth alot of money. I think the premium for that feature is something over $100. If you have the extra cash then why not, but I think they are overkill for the vast majority of riders. Most folks have decent roads and trails to ride on. Even if they are not the best, they are not riding on them for hours with the kids. If you spend more than 4 hours a week on rough trail/road, then sure. Otherwise, don't think twice about saving the money.
I think the Chariots offer more attachment/configuration options than Burley, but most folks don't use them.
Your kids will start to cycle out of the trailer around 4-5 years old as they start on their own bikes or you decide to do some sort of attached riding (multi-seat bike, TAB). You should have no problems selling a Burley or Chariot for decent money in a few years.
Whatever you get, use it. Nicer trailers are too expensive to be sitting around.