I've never had a tour given by an eastern European or such, but I have had substandard tours given by Scottish summer help. It doesn't have to be that way; I've been given very good tours by temporary student guides. It's all down to the distillery's attitude, more than anything else.
Gordon, we loved the older gent at Caol Ila, and were sorry we had not alloted enough time for him (we had to run off to Jura). I can see how he might not handle a larger group well, but if you can put yourself in a frame of mind for a good blether (on things other than whisky, often enough), he's a good chap.
Which leads to my advice for r900p. Every distillery in Islay is different, and all are worth seeing, but don't make the mistake of trying to squeeze in as many as you can. Do one in the morning and one in the afternoon, as a rule; at the least, allow two hours plus travel between tours. You may not need that long, but it's better to have a little time to kill between each one than to wish you could stay and natter for a while when you have to rush off to the next. If you can't get to all you want to, you have reason to return!
Many will consider Caol Ila the least interesting distillery in intself--it's a state-of-the-art facility for the 1970's--but as Gordon said, the view from the stillhouse makes it worth it. I think Bruichladdich, Jura, and Ardbeg are the most interesting, and I was pleasantly surprised by Bowmore this past year. But if someone else said Laphroaig, Lagavulin, Kilchoman, or Bunnahabhain was in his mind the best, I would not argue--as I say, they are all worthwhile.
The latter has distillery visitor info, including tour times, here