While I think Le Cellier is worth it for lunch, I still feel it is horribly overrated. Biergarten is fun, we had a decent meal at Les Chefs and we also had a nice meal at Rose & Crown. At some point, we also want to try Teppan Edo and Via Napoli.
We live in Texas and have vacationed in Mexico, so La Hacienda and San Angel are pretty far down on our list of places to try in Epcot. Tutto also gets pretty cruddy reviews and I'm very picky when it comes to quality of my Italian food (grew up outside of NYC)- so I don't see that happening either.
Marrakesh is the only meal which I'd TOTALLY advise against. We are about as far from picky eaters (i.e. I'll try anything at least once) as you can get and this has to be the worst meal we've had anywhere at WDW. Horrible food and super slow service. The pretty atmosphere could never make up for how bad it was.
Someone noted Bistro de Paris, and while we're good with fine dining (and pretty much any TS dining)- even with our young kids w/us (ages 2 & 4 our last two trips - 10+ts meals each trip for the girlies)- read the reviews before going the Bistro route. Between poor reviews and friends w/first hand bad experiences, Bistro de Paris is also very far down on our list of places to try.
Unless you are really into characters - I'd skip Akershus and Garden Grill. We also fully agree on skipping Coral Reef- definitely on our been there done that list.
While not in the park, you could always leave Epcot for a nice meal at one of the nearby hotels. Yachtsman, Shula's, Bluezoo and Il Mulino are all coming to mind.