One of the features you'll find on just about any double din receiver with an LCD screen is support for a reverse parking camera. The displays on these head units are excellent as it's similar to a factory integrated backup camera and screen combo. We prefer it to the typical aftermarket screens that are either mounted on the rearview mirror or as a standalone unit stuck to the dash or window. Not only are double din screens typically larger but they often have illumination trigger wires so they won't be too bright at night or too dim in the day.
This Sienna owner opted for the Pioneer MVH-210EX receiver which has a 6.2" resistive screen. This is a popular head unit as it has a snappy response and good price point for the up-market features included. These features include 6CH RCA preouts, variable illumination, 13 band EQ, and time alignment settings. With a parking brake bypass, you can even play movies through the USB port off of a thumb drive/memory stick!
In addition to the double din and backup camera, our customer also added a backup sensor kit for audible alerts. The backup sensor system we installed his its own individual display with a distance gauge. It is not tied into the aftermarket radio. The sensors typically come in black but can be paint matched for a more factory look.