Is Don Khong worth a visit? I'm in Laos for only two weeks in total and am not really a 'beach' person by friends have raved about it. Worth 2 days? Less? More?
Khong has no beaches, it is a very quiet, large island worth exploring by bicycle or just sitting around drinking beer and watching the world go by.

I think you're better off at Don Khon not Don KhonG island. Its next to the party island of Don Det. Its very quiet and you can rent a bike and cycle to don det if you want by crossing the bridge connecting don khon. there is a nice waterfall called Khone Phapeng worth a visit. You can walk to the South of the Don Khon island to see dolphins - about 5 kms. Overall, its just nice to chill and read a book.