I've been using one of these on nearly a daily basis for a couple of years now. My girls are now nearly 5 and nearly 3 and fit in in fine.
The explorer is cheaper than chariots but has been sturdy enough during continued use and abuse. Has a massive pocket at the back and folds pretty small. I wouldn't want to use it on really rough stuff but find on firm off road tracks.
You want to make sure, whatever you buy, has:
20 inch wheels minimum
foldable and wheels easily removed
Big pockets
Ability to add a third wheel and use as a buggy is handy.
They are great and much easier to tow than you would expect, but you will know about it on the uphills! I now tow this with a 1 year old in a bike seat as well, I reckon between the 3 kids, trailer and bike seat i am dragging about 50 kilo's!!!
I agree that drivers give you a wide berth, they really do slow down and give you plenty of space, much more so than normal riding without the trailer.
Old photo but you get the idea!