I've got an idea...
Let her choose. Go test drive all of your choices on one sunny Saturday and let her make the call. You appear to be "allowing" an inordinate amount of female involvement in the decision here but, as we all know, it is too late for you to take the reins back away from her.
Why does she want an SUV over a minivan? You say she is a soccer mom, and there is no better soccer mom vehicle than a Chrysler T&C, Honda Odyssey, or Toyota Sienna...
Child/infant safety is much more a factor of choice/style of childseat used and proper installation of it. Everybody knows you stick the kids in the back and use the correct style of seat for their age and size. Frontal crush zones and legroom intrusion statistics don't make a rip about child safety. Also variable-speed airbags are a significant concern for frontseat riding youths (Mercedes does these).
If, bless her heart, she is "better" than a minivan and MUST have an SUV, then you have lost that battle...
I agree that the Envoy/Trailblazer is one HECK of a good package in the size range you have mentioned. The X5 gets consistently high crash ratings and passable reliability numbers (be sure to buy one with plenty of remaining warranty).
I've driven all of the above, and like the feel of the ML's (I actually prefer the 6 cyl over the V8 when the money is figured in). The MDX drives great and has the Honda "look and feel" inside (which is a bit of a turnoff for me, but is quality hardware).
The Jeep products do not rank with the Envoy/TB in my book. The 4-runner is a good unit but is dated. The Sequoia has proven to be reliable but has a cheesy interior for a topline Toyota. The Landcruiser/LX is overpriced and a gas hog - otherwise a fine choice.
My soccer mom ditched her Vette for a Sable when #1 son came along. Baby #2 resulted in a change to a Chrysler T&C, which was probably the ultimate mom machine. The SUV bug hit and went straight for a Yukon XL with TV's, big fat tires, chrome wheels, and billet hardware (why women go for these confuses me). She is now happy with her 14mpg battlewagon.
I lean towards minivans for moms. Safe, economical, flexible, roomy, and the suckers drive great. My company keeps one for business travel and it stays in my driveway most of the time. I probably drive it 30% of the time (hauls boat parts great).