I wish I saw this thread sooner-I tromped through that fish tank last year. Guess I can offer a few bits of advice:
1-Eat before you get there. No outside food or drinks allowed, not even gum or straws. And they search your bags before ya enter. And the food prices inside are absurd.
2-They have automated kiosks near the entrance where you can buy a ticket. I didn't see them because the line to get my pre-purchased ticket was almost 2 hours long. I was seeing folks that used the kiosks get in almost as soon as they bought their tickets! BTW, they have this little area just before the entrance where they take your picture for souvenir sales-just another annoyance trying to get into the place.
3-The bathrooms nearest the entrance were the most-heavily used. The ones in the upper level over the food court/highway robbery area were the cleanest, and sparsely-occupied.
4-One of the staffers there told me that the best time to go is on Tuesday mornings-they aren't very crowded then (I had gone in on a Saturday in July-couldn't get time off of work).
5-There's an observation bubble in the penguin exhibit. You might want to hold your breath when ya enter it-there's no air circulation and the sweaty stench of 40 people was soooo pleasant to experience.
But at least I got this shot for my suffering:
6-While the larger areas, like the central hall and the food court/money vacuum are well-lit, and the sea lion & penguin exhibits are partly outside, I found that the rest of the place was lit like a freakin' cave. The swamp-life area was particularly dark, IIRC.
It didn't help that I was tooling around with just the kit lens & a DA 50-200 then, and I didn't have the Katz-Eye and O-EM53 that I now use for my 50mm 1.4. That and my staggering inexperience back then made it a miserable time for me. I took over 1500 pictures that day (I bracketed a lot) and I hate almost all of them. I think I'm almost ready to go back-I now use a Sigma 17-70 instead of the kit lens, and I have a brand-new Tamron 19AH, along with a monopod and a slightly-better idea of WTH I'm doing (I think). I'll either shoot RAW this time, or try using Flash white balance since everything's so blue; trying to color-correct all those jpegs I got last year was a freakin' nightmare. I'd like to get the K20d to replace my K100 (better viewfinder and the live view to verify manual focus) but realistically that's not happening anytime soon.