I have found that Seafoam if used consistently in small amounts (maybe a shot or two's worth per tank) keeps the bike running consistently.
When I wintered the bike, I filled up the tank and added nearly half a can, and then did one last ride to rack up 60 or so miles. The bike started better than my car through winter. This season I have been busy with other things and let the Seafoam practice slide.
With that, I normally ride enough that I never have had the rougher running crop up- but this year has been a bad year for tires. Although I've spent hours reading up on the merits of plugs patches and the merits of each- the shop just called me and let me know that my 3rd rear tire has now been installed. It's been a good year for them.
So- the bike has had these intermittent spurts of use, and then sitting, and at this point I think what needs to happen is a can of Seafoam and [finally] putting some good highway miles on.