Quality by Design

We are having a difficult time regulating our radiant heat system. There are 3 thermostats in our house. One in the bedroom that also heat the bathroom, and the whole left side of the house. Unfortunately, we like sleeping in a cool room, however, if we turn down the heat at nighttime, the bathroom is cold in the morning. What we have tried to do is to turn the heat way down during the day which takes about the usual 5 to 6 hours to cool the room down, and then we turn the heat back up before we go to bed so that by morning at least the bathroom is warm enough for our showers.
The other thermostat is located down the hall, which heats the living room, dining room, kitchen and hallway. That's comfortable enough if we leave it at 70/72. However, as spring approaches where the nights are cold and the days are sunny and warmer, the heat makes it almost unbearable so we need to open windows which cools off the area, but as evening approaches and the sun goes down, the area is so cool we need to turn the gas fireplace on to heat up the living area.
We also have a four season porch where the other thermostat is located. Right now, it is set at 65, but with the sun shining through all the windows, the thermostat reads 81 degrees. Tonight however, when the sun goes down, it will drop to 75. But, the floors are ice cold all day.
I must say that I am not entirely thrilled with radiant heat. I have always been use to being to turn the thermostat up to a comfortable temperature and within minutes feel the affect.
Is there a solution to our problem. We are heating an 1 level home of approximately 1800 sq. ft.