It needs to be pointed out that UG does give specific which-park-which-day recommendations. I know they are available at their web site,
www.touringplans.com, where they are occasionally updated. I think they may actually be printed in the 2006 edition, though I can't be sure since I don't have it in front of me; it doesn't really matter as you may as well use the online version anyway. The UG recommendations generally avoid EMH parks, which works well most of the time. (Obviously if you want to actually go to EMH you'd have to go against their recommendation!)
I haven't tried TGM yet, so I can't comment on it. I'll probably give it a try sometime this year. Given the prices of the two products I can't imagine them being an obstacle to using both if you wish.
My experience with UG is that they do give you plenty of general explanations so that you can modify their specific advice on the fly. In other words they don't tell you why attraction A comes before attraction B in their touring plan, but they do tell you why certain kinds of attractions must be done early while other can be postponed, how the crowds tend to behave in general terms, how the fastpass system works and when to use it, etc.