I use RoadRunner as my frontend, primarily because it's free, can do what I need (with enough setup) and has always worked well for me.  The skin I use is LSX , developed by Liquid_smoke on the MP3car forums.  This seems to be the most developed skin by far for RR, and since a frontend is nothing without a good skin, it seems to make the very most of RR for me.

 <insert screenshot of main menu>

LSX version 1.5 came as an installer, whereas previous versions were zip files.  The installer makes installation rather foolproof, and by using it instead of unzipping and manual installation, everything worked better immediately.  LSX 1.5 comes with support for iGuidance v3 by default, which pretty much worked immediately as well.  However, I wasn't 100% satisfied with the way it worked.  The configuration of skinbedder that is included embeds a couple of buttons (OSK and menu) on the left side, which look very centrafuse-esque, not matching the skin in use, and they overlap the existing menu button in the program, and the IGCONTROL slide-out menu button.  Also, the right side of the bottom pane (displaying speed) is distorted and unreadable by something skinbedder is doing.

<insert screenshot of skinbedder embedded iguidance>

Because I had used it before (and didn't have much time), I chose to skip skinbedder and try using iGLaunch.  This just involved changing a line in the exectbl.ini in the skin directory.  It took a few tries, but now it embeds iGuidance without the unwanted skinbedder-added buttons, but still includes the slide-out menu that IGCONTROL provides.  I haven't decided if I want to keep that, but it's not very obtrusive so it's not in the way for the time being.

 <insert screenshot of iglaunch embedded iguidance>

 One issue I have run into is when resuming from hibernation, iguidance isn't embedded anymore, and I have to exit RR, close IG, start RR again, and let it load IG over again.  It's not a gigantic issue, but it would be nice to not have to mess with it like that every time I stop for gas, etc.  Since I am very, very new at adding/modifying skin commands, using iglaunch, and using skinbedder, I expect to resolve this issue some other time, when I have more free time, and more experience.

 The other addition I made was the use of iGMon to automatically pause the music in RR when iGuidance was speaking directions.  It also has some other features, like automatically switching to the GPS display whenever a turn was coming up, and then returning to the previous screen after, however those weren't priority features for me so I didn't take the time to make sure they were set up properly.  (and I'm not even sure they're compatible with ig3)  In any case, all I really did was download it, run the setup, and follow the instructions.  Then I set the iGmon app to run on windows startup.  

 Anyway, I've still got a number of things I'd like to work on with the skin and IG integration, such as changing some buttons around since I don't use satellite radio, photos, etc...  Hopefully once I spend some more time meshing IG better with RR and actually understand what I'm doing, I can make this into a more directly useful setup guide for others to follow.