In reply to the.last.thesaurus:
This isn't intended as a criticism of the fact that you have asked for suggestions on a walking / climbing forum, but how about scouring secondhand bookshops or sellers of secondhand books online, for ideas.
There are loads of books about wandering in the Highlands. "Hamish's Mountain Walk" by Hamish Brown has cropped up on this forum recently. All of his other books that cover the Highlands are well worth looking at. The Ken Wilson / Richard Gilbert trilogy "The Big Walks", "Classic Walks" and "Wild Walks" have lots of really inspirational stuff as does Irvine Butterfield's "High Mountains of Britain and Ireland".
Anything by Tom Weir can provide inspiration for a trip along with other older authors such as Adam Watson, Brenda Macrow, Robert Adam and numerous others depending on what you want to get from your wanderings. Many of these books can be found pretty cheaply.
Many of my favourite Highland trips were inspired by essays or even single photographs in such books. Often my trips were done by train and postbus. Although the latter don't seem to exist anymore there are still other sparse bus services across the Highlands.
Sitting on the lounge floor on a winter's evening amongst as many books and maps as you can find is almost as enjoyable as doing the actual walks. Add in the internet with the rail maps and bus timetables and see where it leads you. Some compromises are often necessary to fit in with sparse public transport. Train and / or bus to the start, then walk back to 'civilisation' was always my favourite way of doing things.
Post edited at 23:08