Will definitely be missing Water World in Concord, SF always included it free with a SFMW pass, sure was nice having free access to a decent sized waterpark. Will absolutely be missing my favorite attraction the most, all the free eye candy of hot half nekkid dads! ;o)
IMO SFDL and EV will continue to operate as parks. SFDL is out in the country away from high land prices and has a potential buyer that wants to continue operating it as a park. EV is in a region that has relatively few parks. (although I could see the possibility of EV ultimately being scrapped in favor of a bigger park).
In haven't been to any of these six parks but had I been, almost certainly the thing most missed would be one of the SFMM coasters. Some of these rides were very unique and many used the terrain effectively.
I haven't been to any of these parks, but I would be bummed to miss out on Gold Rusher and Ninja. I get a kick out of mine trains and Arrow suspendeds, and I really love terrain coasters, so not being able to ride these two would be my biggest regret.
I guess I should add Revolution and Tatsu too, because if the park closed those would probably be lost as well.
Being from CT I've only been to SFMM out of the 6, but I'd def. miss Ninja-- it honestly surprised me when I rode it, Gold Rushers nothin to write home about.. I would be upset about X too...
Tatsu I wouldn't honestly, went to the Media Day Campout for my birthday and I'd have to say it's not the best coaster in the park.. don't get me wrong it was good. But the pretzel is not for the weak at heart :)