Nice that such a great car still gets some exercise now and then.
You don't really need to "feed" modern paint like your Glasurit. Older lacquers do require such measures but not your type of basecoat/clear. Functionally speaking, all you need to do is protect it against all the stuff that can damage it.
There are numerous mild polishes you can use to remove the marring. There are *much* better choices than the Griot's; I just used some of the Machine Polishes on a loaner car (thought I'd use these products it up on a car that doesn't matter to me) and it was a reminder of how lousy those products are (I ended up using other stuff even on that). There are good products from
Meguiar's,
Menzerna, and a host of others...The following suggestion is just one approach, but is based on considerable experience with metallics and paints such as yours.
Since you don't sound like you want to get too aggressive with your paint, I'd recommend 1Z Metallic Polish. It's very mildly abrasive, along the lines of Griot's Machine Polish #3 (maybe even *too* mild, in which case use 1Z Paint Polish first) and has some mild chemical cleaners. The 1Z polishes give a *very* impressive "pop" to many metallic paints, they really have a unique effect in that regard, and they leave a little protective wax behind. Some minor hiding of flaws too. I'd top the 1Z MP with
Pinnacle Souveran wax and spray some FinishKare 425 on after that (I'd also use the FK 425 for wipe-downs at shows).
This is the kind of combo I use on my '85 Jag (18K miles, original paint; not your SL but still something that's not a driver

).
Be sure to use very soft MF towels to buff off the polish and the wax. No point in getting things nice and then marring them up with crappy towels.
Man, working on your SL would be a true pleasure. Detailing its suspension and that big six is the sort of thing I'd just *love* to do....you'd have to drag me out of the shop. Real piece of history you have there.