This is the thread that attracted me to this site.
I too live in St. Petersburg...on the west side, near St. Pete General (yeah I can see it from where I am...WAY too close to a place were many will go in the beginning of an outbreak).
The Pier...hmmm.
If there was time to procure/move a couple of those "sail"boats from the Municipal marina over to the Pier...as a way to escape if the SHTF...I think that the Pier could be do-able. At least as a temperary shelter.
The Pier has some bad points as a long-term shelter. Some of those have been mentioned already.
But there are some good points as a temperary shelter.
One being that access road. One way in, one way out (except there are those sailboats someone has brought over from the marina

).
I do not know at what distance the undead would be able to notice/see/smell/hear a group of survivors, but that access road could be blocked with cars/trucks. That might stop/slow down the lethargic-style undead, but would be ineffective for the in-shape, fast-moving style of the undead.
Food would be less of a problem. Fishing is pretty good from the Pier and there would be the pantries from those restaurant(s) inside the building to supplement whatever survivors bought with.
As for other 'locals' having the same idea...only if the Pier was being used as a water-borne evacuation point would a lot of folks head to it.
This is a penisula. This is hurricane country. Heading to someplace close to/on the water isn't the first thing that would come to mind for most of the local population. We are always told, in the event of an emergency...GET AWAY FROM THE WATER!
There would be some survivors that would have to retreat to the Pier, but I don't think that "thousands" would have the same idea...or the oppurtunity...to make it to the Pier.
Unless your "right there", the Pier is going to be a tough place to get to. You have to travel though the heart of downtown St. Petersburg to get to it.
This is the highest density (population) county in the state.
And St. Pete is probably the most densely populated area in the county.
As you know, being another local, there is about ZERO undeveloped land south (and not much north) of Ulmerton Rd.
As a temperary shelter and with only one access road to defend (and those sailboats as a way out/off)...I think the Pier could be OK.
Here comes the 'but' part, "IF" things aren't that bad during the initial outbreak, the Pier may very well be the worst place to be/go. With all the water-front parks, local/state/fed's could very well set-up field hospitals and shelters in those parks and use the Pier as a local command center.
I will not be going to a place were there is a strong possibility that the soon-to-be-undead would be taken for treatment/shelter.
There are a number of walled communities and campuses in the area.
The Admiral Farragur Academy and Eckerd College, just to name two campuses.
But the drawback with these...the number of other survivors needed to guard the walls.
Being residents of Pinellas county means we're pretty much screwed.
Sheltering in-place seems to be the best option, to me, until I can find out how bad things get.
I definately don't see myself heading to a government run shelter.
If I could contact a group of survivors that are at the Pier and I thought I could make it there, I might try the Pier.
But I'm closer to the Gulf. Finding a way to get on to someone's sailboat that's heading offshore to wait-it-out....that's a plan after temperaryly sheltering in-place.