The Month you choose will give you: In May, less of a crowd to deal with but, the fishing offshore is Just getting started the King will not be in strong yet and that is a nice fish for sporting fun to catch. 2 per person limit. However, In MAY you take the chance the Kings are not in yet, and too early for the JUNE 1st till? ending sometime in July Snapper season. So either May or August miss Snapper if you where going to fish more than 9 Miles offshore for Snapper.
August will have more of a crowd and more fish as a general rule, offshore to choose from. If its all about catching fish, August might be the better pick if its about a nice time and less people in Port A and Lazy town feeling May be your month. Either month will be a great experience, but if fishing is your focus I would pick August.
As far a guides I fish mostly Party Boats and all three docks, there do a good job on catching fish, Fishermans Wharf with Larger AC catermans, Deep Sea HQ, with a good fleet and Dolphin Docks as well. I fished all of them, BUT, if you have the budget and want to fish a 4-8 people charter a boat, hopefully someone else will drop their thoughts in... Have A great time and hope to see you at the dock....