I've tried Ubuntu a little, but I use Fedora most of the time. I find that I can do just about anything with the GUI and only need to use the command line for a few specific things that most users wouldn't need to do once it's all set up and going. Even then, I think a lot of users could probably install it and use it without ever needing to use the command line at all. Also, I find that a few quality minutes with Google will give the commands I need for whatever I need to do with the command line. Saying that, however, I do use the command line for a lot of things that I could do with the GUI because it's just easier and more efficient.
From what I understand, Ubuntu is even more user-friendly and aimed at general users than Fedora is, so I expect that one could probably do even more without ever opening a terminal in Ubuntu than Fedora.