Go how? Bus, car?
Do you plan to try and climb Ben Nevis? If so will you have proper gear? Ben Nevis kills people you know. Not because it is a particularly hard walk up but because the unpredictable weather can surprise the unprepared and can/has result/ed in disaster.
Fort William is a tourist town primarily with little intrinsic appeal unless you are looking to buy a William Wallace sword copy and cry 'Freedom' from time to time.
The Isle of Skye has beautiful scenery and frequent rain, so I hope you are planning to pack good waterproof clothing.
On Loch Lomond there is an impressive hostel to the southeast. It is a baronial mansion and comes complete with resident ghost. http://www.hihostels.com/dba/hostels-Loch-Lomond-SYHA-050009.en.htm