the Sand Dollar is one of only a few so cal boats I have yet to dive off. HOwever, I must say (and Im surprised by others opinions), diving with the Sealions, especially if at SBI, is one of the most memorable experiences. I have had some amazing encounters there, and although the picture was not the best, I witnessed an amazing event with two sealions embracing eachother. I for one am always anxious to get out to play with the sealions at the rookery...I wouldnt necessarily suggest a whole day there...but one or two good dives is a must, especially if you have yet to experience sealions close up.
The reefs on the other end of SBI are great as well...so hopefully you get the opportunity to dive those.