I've been creating a bunch of similar graphs lately.
So for each one, I:

a) select the range of data in calc
b) Select insert->chart
c) Select Line, and then Points & Line
d) Add the 'first column as label' tick (with the existing data in columns, first row as label)
e) Confirm the data series
f) Fill in the title, subtitle, x axis, yaxis - of which only the Subtitle is varying.

That gets repetitive; I'd like to be able to save b-f as 'audiosweep' or similar.

From a UI I'd suggest:
  a) As well as Next/Cancel/Finish in each part of the Chart Type dialog there would be a 'store'
     a.1) The 'store chart' dialog would contain which elements you wanted to store with a set of tick boxes (Like past special); so I might not store the Title or Subtitle or ranges
     a.2) It would let me pick a name, and if I wanted I'd be able to choose to modify an existing one.

  b) The 'Insert Chart'->Chart Type gains a User section at the part of the list