I have been very impressed by Meguiars Interior Detail Products.
D106 Fiber Rinse and Tannin Stain Remover and D116 Protein Stain Remover are the best I have used to date for cleaning, especially with steamers and extractors.
They are exactly what I look for in regards to interior cleaning for carpet and upholstery.
Clear in color, unscented, can be diluted way down, and can clean any dirt and stain.
Meguiars D102 Foam Carpet and Upholstery Cleaner is a great way to finish as an LSP in tandem with the above products, or use by itself for light cleaning and maintenance details.
Has the best, freshest scent of any foam cleaner that I have used and I think it is perfect in that regards.
Griot's Garage Interior cleaner is probably the best all around interior cleaner, as it can not only clean, but leaves a great finish on panels, the dash, console, etc...
For tough stains, such as heavy grease and mud, stains you think might be impossible to remove, there is none better than Rapid Remover.
This product is expensive, but I have yet to meet a stain it can't remove, especially with a steamer, extraction, or Tornador.
This product will always have a permanent spot in the detail inventory.
It is awesome, and smells great too.