I think what you are doing is a good way to do it but you might want to search this forum for “parametric bench” as I have seen some similar shapes that have been benches rather than wall art.
Perhaps there is some magic definition that always produces beautiful surfaces but I think it is more likely that you have to search for the magic set of parameters within your model that produces something beautiful. Maybe add more parameters / control if, like you say, you want to have greater control over certain details.
I spent ages tweaking a definition described in this discussion…
FORCE FIELD
To begin with I thought my definition didn’t have enough control to produce something I liked but eventually I found a set of parameters that I liked on the screen. I turned this into a panel above a window on my house and I’m not sure I like it 