I found Everest to be something of a disappointment, from the standpoint of service and cuisine, but the atmosphere is lovely -- the view of the city is wonderful (it's on the 40th floor) and the room is very elegant. And do know that, while it's French, it's Alsatian, so it leans pretty heavily toward the German. In fact, the creamy sauerkraut soup was the best think I ate there. However, I will say that, while I know a lot of other people who have been disappointed by Everest, I also know that a lot of people love it, so perhaps it's just uneven. (And just so you know, it wasn't bad, it's just that it has so oftern been voted "best in Chicago," my expectations were high. Because it wasn't.) But the setting is flawless.
At Tru, I found the food to be better, though I'm not a big fan of Gale Gand's desserts. The service was flawless, but the setting is a bit austere, if what you're looking for is atmosphere.
Here's a recent thread on Tru:
http://www.lthforum.com/bb/viewtopic.ph ... hlight=tru
Though I've seen many posters say that Everest is their favorite restaurant, I've never seen a discussion of why. But at least I know some serious eaters had a more impressive time than I did. If you do pick Everest, be advised that it's a bit of a trick to get in -- if you park there, the entrance is on the side of the building opposite the street address, and then it takes three elevators (only two, if you come in at street level) to get to the restaurant.
I do think that you'll have a pretty good time either place. And as for atmopshere, I interpret that to mean romantic and European, but if you like techno-hip, Tru might have a better atmosphere. Enjoy whichever you pick.