Nature
Scotland is definitely a place that rewards nature lovers of all types. Its specialty might be wild and remote scenery but there are a surprising amount of lovely Gardens too; as well as a number of place to view wildlife or observe them in zoos.
One pleasant way to combine all these things is on a boat trip – and there are quite a few options around Scotland too. Among the best are Loch Katrine, in the Trossachs; and from Elgol on Skye. But if it's just seal-spotting you want to do, try the short trips from Plockton.
Similarly some rail journeys also allow you to really enjoy the scenery – try taking the train from Glasgow to Oban or Mallaig – taking the Jacobite Steam Train for the latter journey if you can.