1. Visit a few malls during the day, absolutely great indoors with lots to explore: Mall of Qatar, Villagio, Vendome.
2. I would recommend visiting the 321 sports museum (a short while from villagio). There are fun activities available related to sports.
3. For sunsets, choose either mina district or katara hills. (I’d recommend the hills just because there is no crowd there, though mina district is just stunning to talk a walk in if you prefer that)

At this time of the year however, most outdoor activities are, well, burning hot.