Thank you to all the previous posts that helped me pick out restaurants for my visit. It is hard to judge a restaurant from a single visit especially with just one diner, but here are my impressions. Sorry I couldn't remember some of the details.
Aguila y Sol was by far my favorite. If I go back I would go there and also give Tezka another try.
Aguila y Sol (Polonco). This was my favorite meal in Mexico City, probably of the trip. Modern minimalist style where diners seemed to be rather stylish in a variety of dress from upscale to casual jeans. I arrived at 5pm and it was packed but by 6:30 it was half empty. A lot of smokers. Excellent service. I started with the squash blossom soup which had a mild curry seasoning. In the soup they added many ingredients that added texture and subtle flavors cuitlacoche, almonds, thin pepper curls, and some cubes of maybe a mild cheese. For the main course I had the duck negra mole. The sauce was a medium spice rich mole. Plantains provided a nice sweetness to balance the spice and richness of the duck and mole. The only disappointments were the breads and tortillas. They were pretty bad, tortillas seemed stale.
Tezka. Maybe it was that I was tired from the trip, I ate here the night I arrived. I thought it was good but was not wowed considering this is a Michelin 3* Spanish chef. If I had not read a lot about this restaurant I might have left when I arrived around 8pm and I was the only one there. I had 2 appetizers instead of a dinner. The first was a shrimp and passion-fruit. The shrimp was very rare (maybe raw), and the shrimp legs where crispy and off to one side. Although I like sweet shrimp sushi the rare shrimp was a little much for me with not enough flavors to mix in. The second dish was foie gras with cheese in pockets. These were in a thin puff pastry style with very creamy filling, also on the plate was a mixture of nuts, basil, and small melon balls. This dish I enjoyed the flavors and textures. Service was excellent and accommodating. There were a variety of amuse bouche. Bread served was a variety of hearty grain breads which were very nice.
Don Chon (Regina 160@Jesus Maria)– low key restaurant specializing in prehispanic cuisine. Although I had read somewhere the neighborhood was rough, it seemed very safe walking with businesses everywhere which catered to locals. I had hoped to have the ant larva, but they were out. I opted for the chapulines (grasshoppers). Very crunchy, salsa added some flavor. They were okay, and now I can say I have had them, but probably would never order again. I also had some mushroom quesadillas. They were excellent. The chef was very friendly, came over to take my order and stopped by later.
Panaderia Ideal – A huge Mexican bakery. There are two locations near the historic district. I loved browsing and picking out some treats. Very reasonably priced. They carefully wrapped everything up for you.
El Tajin – middle comfortable environment. Nice open air section to enjoy the beautiful day. Excellent tortillas with some sort of herb inside. I had mixed appetizers, mostly fried dishes that were okay. For the main course I had the shrimp in tamarind chili sauce. Shrimp were cooked nicely - not too done, still tender. Sauce was sort of a sweet and sour.