harbor,
I've tried the Meguiar's Natural Shine, and still use it in my engine bay (diluted 50/50 with water). Leaves everything looking new, without a greasy, plastic type shine that only attracts dust. I've used it on my dash, trim, and tires, but it has a bit too much shine for my tastes on those surfaces. It's not nearly as shiny as some others, but I prefer a matte finish on my dash like I get with 303 (I used Vinylex, also, which is in between 303 and Natural Shine in the shine department). All 3 of the above products are good, it just comes down to personal preference. 303 and Vinylex make tires look outstanding, too!
I get 303 Protectant from a local RV center. Boat shops sometimes carry it, too. It is more expensive than others, but I feel the results are worth it.
Dave