I've never used a fishing guide service before, but if I were to use one in SD I would have to go with Conway Bowman of Bowman Bluewater Guides & Outfitters. This guy is a remarkable and well known flyfisher.
Oh and did I mention he can put you on Makos with bass gear and on the fly? 8-)
Here's the link to his site:
http://www.bowmanbluewater.com/
I think he also offers guide services on SD's local freshwater lakes like Hodges, Dixon, Poway, etc...
I hope this helps.