Hmmm none to compare to AG and I don't really go downtown per se for dinner as the best dining is elsewhere. If I remember something I'll post but if you want to be in downtown Departure is amazing - futuristic decor, views, Asian fusion and Gregory Gourdet was in same top 3 with Doug Adams on Top Chef. Memorable.
If you go to the Pearl, which isn't far from downtown Blue Hour is good and has Italian inspiration. Going in that direction there are a plethora of good places to check out: Tasty & Alder (American), Gruner (German but the real reason to go there is the burger in the small bar during Happy Hour - The Best!, Andina (Peruvian - great Pisco sours and ceviche). There are 2 Italian restaurants that I've heard good things about Piazza Italia and Il Gallo Nero but haven't been to either. I'd rather walk to Ava Genes.
When are you going? Reservations will be needed at most of these places and they get booked out. If I decide to go on a whim, I usually go when they open and try to sit at the Chef's Counter. Hope this helps and that you have fun here in Portland!