Scottv...I do not hesitate to use raisins in my mead. They are a great nutrient source for mead, and we know that nutrient deficiency is an issue in mead--unless you tackle it. If I am working on what will be a light colored mead I use golden raisins or a blend of golden/dark. I typically use 8-12oz per gallon. If the mead will be darker then I use plain dark raisins, though zante currants are my favorite dark 'raisin'(though not a raisin, but you know what I mean). I do not worry if the raisins have sulfites, but I do look for oil and avoid those particular ones. The amount of sulfites added to preserve the raisins will not inhibit your yeast, but you can do a few rinses in boiling water if that bothers you.
I will also haunt nuts.com because they have a huge variety of raisins, and sometimes I even find the raisins on the stems--fabulous little dried drops of sugar!
You mentioned you would like to improve your mead. Would you care to share your recipe, start date, bottling date, etc--perhaps we can troubleshoot? The biggest tip, and you may already know is: quality in/quality out, all in good time.