Hi Franz
Personally I would plan my trip around the weather, the west coast has without doubt all you are looking for, but is also prone to the wettest weather
the east side of the country is usually drier and is only a few hrs drive from the west, us being a small country
so I would think a bit of jumping back and forth might be useful.
Agree with the suggestions above, would be worth a drive down Glen Etive while you're in Glen Coe and also a visit to Glenfinnin and Moidart east of Fort William.
Highly recommend Skye as well, but pick your weather wisely.
The Quirang is easily worth a day trip, endless photo opportunities on Skye if the weather is good especially walks into the Cuillin Corries without doing anything tricky, also the boat from Elgol to Loch Courusk would be high on my list too
I would possibly look up the BBC website
http://www.bbc.co.uk/weather/2635167 and get used to how to read the weather
usually the most accurate for a day or two ahead.
Hope you enjoy your trip and you get good weather? because if you do that means we get good weather too