Unless things have changed for the better, which I doubt, I was up there in 1993 and it was fished out as far as shore fishing goes.
I had a cottage at Kilmichael Glassary in Lochgilphead and fished Loch Fyne, Loch Crinnan and all the way around the Mull of Kintyre, including really out of the way places such as Loch Sween and never had so much as a nibble.
Places of interest for a lads weekend away are the Tayvallich Inn pub and restaurant on the banks of Loch Sween which serves the best seafood I've ever tasted and also does an Aberdeen Angus beef curry which is to die for. Distillery tours at Oban and Campbelltown were OK with plenty of free samples.
If fishing is the primary goal though, I would jump on a ferry at Oban Harbour and head for one of the many Hebridean islands where you'll stand a much better chance of a fish.
I'm heading for Ayr this summer and by all accounts the fishing ie non existant there as well.