I do not use spreadsheets very often.
I do not make graphs from data very often either.
However, I had to make some graphs for my talk at CocoonGT2007.
I used the new Numbers from Apple, part of iWork'08.
I was very impressed. Slick, fast, intuitive.
From never having used it before, I was making what I needed within minutes, you can't say better than that, can you?
I needed to use graphs made in Numbers, within my presentation made in Keynote (the reason I have iWork).
Copy & Paste did the trick obviously, but what got copied?
I expected it would either retain a live link with the original file (like OLE?) or that it would copy over an un-editable object.
Wrong on both counts, it copies a Graph Object that is still recognised by Keynote, allowing you to further edit data there, (or further fudge your results, as the case may be ....... not that I actually had to do that myself of course !! )
It is not perfect, there are a few bugs with the graphics engine etc., shared by the other iWork apps ..... little niggles ..... stuff they will hopefully fix soon ......
There is a 30 day free trial, give it a go.