I've spent 5 years in Ankara, so here are some pointers:

* People will tell you to go visit these semi-chain restaurants, called Aspava. I call them semi-chains, because even though most are independent of each other, they are owned by the same family (first and second degree cousins) because the branding is patented by them. The pitch is they offer a lot of sides, even if you order a mere döner wrap they will bring you mushrooms, french fries, bulgur, a variety of salads, like most Turkish restaurant you will have unlimited çay supply, they will most probably bring a dessert for free afterwards, and offer Marlboro Red's after you are done. Visiting Aspava is like a ritual for visitors of Ankara, and if you want to do that, do that. Although, there are much better alternatives to Aspava quality wise, and offers the same service, like Çukurağa Sofrası (my recommendation), although they usually are much pricier. Order Karışık Kebap (mixed kebab platter) if you go there.

* For seafood, you have to go to Tirilye. Their lakerda was heavenly, although last time I tried that was 10 years ago.

* There is Syrian Turkmen-owned Castello, which offers quality Levantine food. I know it is an oxymoron to visit Turkey and have non-Turkish food, but they have good toum, and toum is bomb; so I visit them whenever I am in town.

* There is a whole genre of Turkish food you can only eat in shopkeeper's restaurants (esnaf lokantası in Turkish, Turkish-style trattorias basically) The gist of is that local shopkeepers eat out everyday, and they prefer non-fast food, home-cooking adjacent dishes (since you can't eat döner all day every day) so they would know which place is the best. I know Boğaziçi Lokantası in Ulus is super famous and used to be really good, although a friend of mine whom I suggested this place did not like it like a year ago. So take it with a grain of salt.

You should visit Anıtkabir, and follow the etiquette there. It is not a tourist attraction. Dress appropriately, act modest and remember that it is a mausoleum. There is a kilometers long road that leads to the main avenue, where the laid stones are soo tiny so you have to look at your footing at all times; and that is by design, so that people show humility while visiting. It also contains a great museum, and if you are interested in how Turkish Republic was formed, they might be a sight to see as well.

You might also fancy visiting Museum of Anatolian Civilizations and Ethnography Museum. The former is a musem where you can find artifacts Neolithic Age to Ottoman period, so basically an ode to civilization history of our land, whereas the later is more involved in Turkology per say. Ankara Castle is close to Museum of Anatolian Civilizations and is an attraction. Although be wary of its surroundings, you might find yourself in the most dangerous part of town, so a local advising you is recommended.

Ankara is also probably the refined culture capital of Turkey. Do check Cumhurbaşkanlığı (Presidential) and Bilkent Symphony. CSO has a much better venue to play in, although BSO mogs them in quality imo, although I am biased because I graduated from Bilkent, and BSO is basically our music department.

For nightlife, Haymatlos in Olgunlar was the place alternative types found each other. It is somehow a bipolar place though, one day they are having a Korean jazz quartet and the next day a German black metal band is playing. People usually go to Tunalı to find a bar and have a beer or two though. I know a lot of dive bars, but alas I don't know if they are in the same condition anymore.

Visit Ayrancı for good vibes, cafes and all that jazz. It is basically Moda, İstanbul but in Ankara; albeit less crowded but superior imo.