I got the led festoon interior bulb almost 12 months ago with the 7 colour changing. The ones I had were not very bright and after a while the 7 colours only become about 2. I would just keep the normal bulb for the interior unless you need to show your car.

The led wedge bulbs are well wicked, but make sure that they have the concave tip on them, not the normal rounded tip like normal bulbs, cause the light points in one direction and doesn't spread. Also look out for the red/blue changing ones.

The undercar LEDS are well worth their money too, much stronger than neons.

At my local car accessory shop (autobarn) we have "light off's" where people come along put lots of neon's, led's, strobe's, smoke machines and anything else we can think off into our cars. it's good cause i dont live in a big city (pop 25,000) and its good having a show after dark, much better atmosphere. It's not just about who has more money, just about how creative you are. I am currently in the process of trying to hook up a laser show to the front of my supra.