Bagan was most highly city for our trip in Myanmar. Quite peaceful and lovely city. You should spend more time in Bagan rather than spending time for flights or if possible I would like to suggest our itinerary as below. But we took overnight bus from to Inle Lake

Day 1: Fly to Mandalay

Day 2: Mandalay, bus or car to Bagan ( this route is very nice), it takes about 4 - 5 hours
Day 3: Bagan
Day 4: Bagan - flight to Inle Lake
Day 5: Flight back to Yangoon