The delta conyne kite is a combination of box and delta, and is a dependable kite in most conditions.  For some reason there are not a lot of them around, but Gomberg Kites, or G-Kites, make them in three colours at a very reasonable price.   These kites can easily be flown in a train, by passing the line through the centre of the kites, and I have three which I often fly on one line.  Some people fly six or more, and if you want an exciting spectacle with a lot of pull, you could go for even more.  These kites are 8ft across, so even one on its own is good.  They are well constructed in ripstop nylon with fibreglass spars.  The price (2012) is only $44, so it is great value for something that should last for years and is easy to fly for anyone.