One week is actually not very long, you could easily spend a week in the Glencoe area and still only scratch the surface.
Under the correct conditions, Scotland IMHO can be amongst the very best places to photograph landscapes due to the quality of light and accessibility of the land.
I would like to know a little more about exactly what interests you, specifically before I'd recommend an itinerary. That said, if I had never been to Scotland, there is no doubt in my mind that I'd be staying West. Now 'West' encompasses quite a bit so I'd personally fly to Glasgow, pick up a car, (absolutely no requirement for a 4x4), drive across the Erskine Bridge and head for Loch Lomond (A82). If you follow the A82 north towards Glencoe, you will drive through some unbelievable locations, with many opportunities right from the road-side. I'd then be heading towards Skye, all the while you'd still be travelling through fantastic scenery.
There are a few routes by which you can get to Skye, via Mallaig, past Glenfinnan/Arisaig then by ferry to South Skye (Sleat) or via Kyle of Loch Alsh and the Skye bridge (no cost). This also opens up the previously mentioned Applecross and the Bealach na Ba (Pass of the Cattle) which is quite a gobsmacking drive.
Skye is, well just Skye, you will NOT be disappointed if your a landscaper.
I'd really need to know more about you as a tog, are you prepared to do a bit of hiking, do you just want accessible photo ops not far from the road ? I could send you up many superb Glens for something that wee bit different but if the missus is in tow, then I guess thats not what you'll be after ?
May IS a very good time of year, as the sun is still relatively low in the sky but it also allows slightly longer shooting days and the sunrise/set isn't just quite at ridiculous hours. There are a hundred other places, where you could easily spend a satisfying week, (not limited to) Knoydart/ANY of the Islands/Sutherland/Inverpolly, etc, etc, etc but if what I'm taking from your OP is correct then I think Glencoe/surrounds and Skye will be perfect for you.
Have a look at my flickr -
www.flickr.com/photos/antsplan (apologies though as its a bit messy in terms of subject matter) and if there are any specific areas you are interested in I can write something up for you.
Best
Anthony