while not material to the discussion of the suitability of the slip, you may also want to consider what amenities they offer that you may or may not be interested in and what kind of yard they have. do they have a travel-lift? they may all have the full Monty, just thought it might be something worth considering.
this is an ok link, more of a link to links but it might be helpful.
Cape May marinas - New Jersey, NJ, United States
oh, i thought Chef made a good point too... id hate to be somewhere dominated by stinkpotters... lol
this is a neat site too which may give you some more guidance.