We spent a week in Appin last September and love the area. If you like walking go to Glencoe for a day. Awesome scenery. There are different kinds of walks there for serious walkers/climbers and also less fit people. We did the Hidden Valley walk which is in all the guidebooks. There's a visitors centre at the north end of the glen.
You're halfway between Fort William and Oban. Both have their attractions as well as stuff like supermarkets. Tesco in Oban and Morrison's in Fort William. Various boat trips go from Oban.
If you go to Port Appin you can get the passenger ferry to Lismore. A nice day out. Try the community cafe. You are handy for the Road to the Isles. Either take the train or drive to Morar, Arisaig and Mallaig. (not much to do/see in Mallaig)

The whole area is one big scenic drive whichever way you go so you can't really go wrong. The A82 from Loch Lomond all the way up to Fort William is stunning. There's a lovely cafe overlooking Castle Stalker at Appin so you may be able to walk to it, not sure.
http://www.castlestalkerview.co.uk/
The views from the Ballachulish bridge are fantastic either side, just north of there is the Corran ferry which is worth a trip on and a drive along the loch at the other side and carry on to the A830 (the road to Mallaig) which has already been mentioned The beaches along there near Morar are beautiful and the Glenfinnan monument is set in a stunning position at the northern end of Loch Sheil.
There is Neptunes Staircase (a set of locks on the Caladonian Canal) just north of Fort William and on a wet day the Cruachan Power Station on Loch Awe is worth a visit.
http://www.waterscape.com/in-your-area/highlands-and-islands/places-to-go/343/neptunes-staircase
http://www.visitcruachan.co.uk/
The A82 carries on from Fort William up to Inverness along The Great Glen which has more stunning scenery and the famous 'Commando Memorial' just past Spean Bridge and Gondola rides up Aonach Mor near Ben Nevis with some walks at the top.
http://www.nevisrange.co.uk/
I hope you get good weather because you cannot beat this area for scenery and there are so many places to visit.

You can walk the Port Appin circuit, which I believe is not too taxing!
http://www.walkhighlands.co.uk/argyll/portappin.shtml
http://living.scotsman.com/autumnwalks/Scotlands-best-coastal-walks.2466234.jp

Some more walking to give you ideas in the local area
http://www.tartanhen.co.uk/appin/walks.htm

Some breathtaking scenery to view on your way - enjoy.

Thank you all very much for the great information. Plenty for us to go at there. All we need now is for the weather to be kind

I`d also recommend having a look at the Kintyre peninsula, it`s beautiful all the way around the coastline, with lovely views across to the islands of Gigha, Cara, Islay and Jura from the Western side, and Aran in the East.

Thank you