Disclaimer: just because something works for me that doesn't guarantee that it's a good idea for anybody else.
Some, *but not all* rubber surrounds respond very well to being cleaned with products like
AIO and then protected with LSPs. I've been doing this on my Jag for a good 20+ years with no problems and I just put Collinite 845 on the surrounds of my previously abused beater-Blazer. This does *not* work very well on the rubber side window surrounds of my Audis.
As for the more conventional dressing-type approach, I like Autoglym's Bumper Care and, for less severe situations, Wurth Rubber Care (aerosol, I spray it on a cloth and wipe it on). These seem to hold up well, even in bad weather even if they don't last all *that* long.
But I've come to prefer the first method if it works on the specific vehicle. People warned me that "the petroleum distillates will degrade the rubber" but it hasn't happened and the Jag's a pretty good long-term test case.