Not many cruise ships have actual single cabins on them nowadays. Cunard and Fred Olson are amongst the few that do. These will be available in various grades, including a choice of outside cabins. So you should be able to find something decent to suit you. Most cruise lines just sell late availability double cabins at a surcharge. I suppose that since they are the ones that are left after others have chosen theirs, then these may well be less well placed than some others! Happy cruising.
On Fred. Olsen many single cabins have windows and a few have balconies too. Try them for size and I don't think you will be disappointed.