Just come back from the Western Isles, a truly magical place you'll love it. This was my route if you have any specific questions feel free to get in touch.
Oban -> Mull -> Kilchoan (mainland) -> Mallaig -> Isle of Skye -> North Uist -> South Uist -> Oban -> Isle of Arran -> Culzean.
My main tip would be to do as much of the Western Isles as time permits. The Isle of Lewis and Harris if possible, I couldn't due to a forced change to the itinerary, but I've heard great things. If you go further south I also heard Jura and Islay are crackin
Oh, and I stayed in hostels. Might want to consider them giving the costs of B&Bs, there are a fair few dotted around, should start to get quieter now too...
Enjoy!