Catch the metro to Hidropark island in the Dnipro river: Kiev is endowed with natural city beaches that line the Dnipro. Many a summer day can be spent in the parks and on the beaches of the islands, where you can buy shashlyk from stalls, play beach volleyball, swim in the river or in the pools on the island, or just soak up the sun.
Stroll around Podil. Start at St Michael's Cathedral in the Upper Town: Catch the funicular down to Poshtova Ploscha, and wander around the grid-like streets of Podil. The area was the merchant's quarter, and was completely rebuilt in the 19th century after fires destroyed the area. It was mainly untouched during WWII and is emerging as a hip restaurant district. Finish your stroll by walking up Andreiivsky Uzviz. You will get back to St Michael's Cathedral.
If you're in Kiev on the weekend, go and people watch on Kreshchatyk: Start at Lva Tolstogo Square and head underground. Walk through the Metrograd shopping center, always sticking to your left. Head above-ground at Taras Shevchenko Boulevard, from where the council shuts down Kreshchatyk on the weekends. Walking up the street to Maidan, you will be treated to the sight of numerous street performers and animal handlers, or you can simply enjoy seeing families out and about for a weekend stroll.
Go to a service at an Orthodox Church: The best one to visit is St Volodomyr's on Taras Shevchenko Boulevard. Services are long and there are no seats in Orthodox churches, however it's perfectly acceptable to come and go as you please. Women must cover their heads before entering the church. Metro: Universityet.