I think almost everyone in my research group uses either Inkscape or Illustrator, me included. The key is building up a good library of parts and 'learning' the workflow on how to do it neatly. If you want a good starting point, I believe there is a good svg library on the wikimedia servers that many in the office here use as a base, but all clean up somewhat to their preferences (I think the linethickness is too large personally).
@UnnamedNewbie did his dissertation in, InkScape I think, just hand drawn figures mostly. Graphs plotted in... gnuplot or MATLAB? That was on microwave structures, so not so much electrical as mechanical schematics.
I started in inkscape, but after a while just caved and gave Adobe my money. Since then all of my figures and graphics are using a workflow along the lines of plot in MATLAB (using a plot formatting script that sets a bunch of stuff like plot aspect ratio etc), export as SVG, load into Illustrator, clean up, export.
For plots that I have to insert into latex (eg for IEEE papers which have a standard latex template you have to use) I export them to PDF. For all other stuff I do, like presentations, reports, etc,... I stick with the standard .ai filetype. For typesetting the actual presentations/reports, I use Adobe InDesign.
One of the main things I love about my Illustrator+InDesign workflow is the use of many layers in the Illustrator file, and being able to select which layers I want to display in InDesign. This way I can make a single figure file (a schematic, or a graph with many different curves and text annotations) and in InDesign select what I want to show in different instances of that graph. This way, I guarantee that all figures will look the same - If I want to rescale the axes, it will update all figures, and I don't need to manually rescale each individual version of the graph. Similarly, if I change the font used in a schematic, it will update all schematics using that same file.
If you are not familiar with InDesign, imagine MS Word and LaTeX had a baby, and it got the best of both worlds.
Illustrator is great but the workflow is horrible. I had to piece together a technical manual once with that and InDesign. Ugh. Kill me with a spoon.
Odd, I personally love the workflow of Illustrator+InDesign. Could you elaborate on what exactly it was you didn't like?
I seem to recall that someone in the office actually wrote a netlist exporter that could parse SVGs generated with a certain library of components and check for LVS and such. Why you would want that is beyond me though.
Here is an example of a figure I did in Illustrator (still not great, since this was in my first month of using the program)
A graph (which really isn't all that clear, in hindsight... Man was I young and ignorant when I wrote my masters thesis)
Here is a schematic of a simple cascode PA:
(note that all of these are png's to upload back then, but the actual documents would have used the vector graphic versions)