Just back and we used the UG 2-day plan for Families with 4 to 8 year old girls at MK, and 2-day guide for Epcot (plus an unplanned evening there), and the 1-day guide for AK (which we spread out over 2 days). And yes, it worked. In fact it worked too well. We did SO MUCH . . . SO EFFICIENTLY . . . and we were
SSSOOOO
TTTTIIIIIRRRREEEDDD!!!!!!!
by the 4th day! We've done Disney before, we're old pros with Fastpasses, but we've never done so much. We weren't planning to do much at Toontown or get any signatures other than the 1 princess breakfast we scheduled, but we had plenty of time for signatures and exploring all the walking paths around the Castle and the Tree of Life. We even had time to stake out front row spots for Spectromagic and Illuminations (waited about 1 hour for each - never done that before!) We rode every ride we wanted to, saw every show we wanted to, and had a sit-down meal every day. We also swam at the hotel every day and spent a few hours at Downtown one day.
So, yes, they work. My advice is, use them for a few days, then GIVE YOURSELF A BREAK! Do NOTHING for a day. Not even a meal reservation! Then go back to touring.