Did Fife - Stornoway a couple of months back. Routed Fife - Oban and then Canna and over Skye to Stornoway. Beautiful evening and very very scenic.
I'd second FBWs comment and route up to the west of Prestwick. Fuel is available at Oban and Stornoway.
I'd also suggest getting a HIAL Out of Hours Permit, costs around £25 and valid at most of HIAL's airports. Download the forms from the HIAL website, fax or email and you should get a pretty quick response. Mine was same day.
Sollas flyin is 10th-14th Sept. Fingers cross we will be there. See
LAA Highlands & Islands Strut Solas Event for more details.
Other places worth of a stop on the way are Coll, Colonsay, Oban, Glenforsa and Plockton. Tiree and Islay have larger airports but less character. Unless of course you can factor in a Distillery visit.