Still playing with the data.

I still use Excel for most things, and then copy the graph as a picture and paste it into a drawing program to clean it up for publications. There are a number of "add-ons" that make it useable, some of which will get it to plot data with error bars, others while permit triangle graphs. I could give you URL's for some Excel add-ons for geologists, but that might not be as helpful as your doing a search for ones better suited to the kind of data you are dealing with.

Now, if you want power to do any kind of calculations and graphs, try something like Mathmatica--it is really hard to set up the formulas and files in the first place, but once they are working it is wonderful...

Ew. Excel both makes ugly graphs and is known to have all kinds of pernicious statistical problems. MS has known some of their algorithms are wrong for years...

I use R (http://www.r-project.org) for data analysis and graphing. It is very powerful and not easy to get started with because of that, but with new addons like R-Commander that provide menus for common tasks it has gotten to be quite straightforward, no worse than any other software package. And it's both free and open source.