I've used a few software packages for site design and other things in my career. I'm a little biased because I "grew up" on InRoads but I also used GEOPAK and was exposed to several others. Out of all of the software that I have seen, InRoads is the best.
InRoads is compatible for use on AutoCAD and MicroStation. These days, that doesn't make a lot of difference for MicroStation users since V8 natively supports DWG files. Nonetheless, it is a great software package to use in a office where different experiences exist.
My experience is that almost every engineering office has AutoCAD users and MicroStation users. The primary reason is that AutoCAD is typically taught in college or even high school. Bentley has been totally ignorant in that fact and doesn't market their software in the education environment. What's the better package of the two? My vote is MicroStation but that are plusses and minuses to both sides. Realistically, it doesn't matter which one you choose. Well, except when your client requires a particular deliverable. Many DOTs require MicroStation files. I understand that AutoCAD will soon be able to handle DGN files and, if that's the case, it comes down to whichever package YOU are more comfortable with.
Back to the Civil Engineering software.
GEOPAK is a pain to learn. I won't argue it's power and customization ability but it's a miserable product to teach someone to use. Even given ample software experience, it took me months to get to where I felt proficient in using GEOPAK. The software has countless bugs in it that causes repeated crashes among other things. It's just not the software I would choose.
InRoads, on the other hand, works similar to any other Windows software package. It has menus. It has toolbars. You can customize macros. The data is "intelligent." It just has a lot of options that you may or may not use. The best thing about it is the ease of use (as easy as any engineering software can be).
The best thing for you to do is to contact Bentley (who owns GEOPAK and InRoads) and get them to give you a demonstration. Some of their stuff can be retrieved online from