Heard about this place a couple of times, and visited it today. I kind of steered my wife toward Seaside based on this information, even though I just spun it to her as "I hear it has a great boardwalk!"

I wasn't exactly sure where it was at, and initially thought it went out of business. There are at least 5 arcades on Seasides boardwalk filled with cranes, slots and Deal Or No Deal but none of them have old stuff except for Flashback. This is located in the back of the Carousel arcade by the Salt Water Taffy place. Its a little bit out of the way, since its in the rear part of another building full of redemption machines. I'm sorry I didn't bring my camera on the boardwalk to get pics, but other people have, and the pics are easily found with google. There is also a video on Youtube.
I played a lot of stuff... Tempest, Robotron (in a Defender cab but with correct Robotron Wico's), Asteroids, Mr. Do, Donkey Kong, Stargate and a Gyruss that needs some monitor work. I heard they had a Defender, but they only have the Stargate now and that is what I played the most. Here are some of the games they have that I didn't get a chance to play:
Frogger (needs monitor work)
Super Mario Brothers, but not a Playchoice. Just some NES based thing? Not even sure. Funny hearing that music in an arcade though.
Galaga
Spy Hunter sit down
Rampage
Mr. Do's Castle
Ultracade that was busted. It was a showcase with a huge projection screen, would have liked to play it.
Sinistar (this machine is beautiful, almost too nice to be on the floor)
Centipede and Millipede
Kung Fu Master
There are a bunch I'm forgetting... They have a bunch of pins too.
I felt the place could have used a couple vert shooters, but it appears they are pretty consistently sticking to a 1983 and earlier theme, very evident in the total lack of late 80's/early 90's fighting games.
My wife thinks I'm nuts. I have a MAME cab with a dedicated Stargate layout at home, but freak out and play it over and over when I an example in the wild with gunky buttons and the rest of the control panel appearing to be made of cigarette burns.
She took the kid and went shopping for an hour while I hung out in there.