Theme it to the area where it is located: Alpine Village for the area next to the Matterhorn, Old West for the area behind Big Thunder, old school Pleasure Pier for this area, etc.
I think the area that used to house the Maliboomer is too small for a dark ride and it's queue, and most flat rides would have to be elevated with the queue underneath to fit in the space, so I'd like to opine a third option: make a pass-through to the area behind the spiral of California Screamin'. There is a backstage access road for parade float access, and there is Disney Way and Disneyland Drive/West Street, put them underground like Disneyland Drive is for Downtown Disney but make the space three times as wide as Downtown Drive.
You can put a dark ride in the newly minted space, a couple flat rides (maybe something like the Riding Derby at Cedar Point, or a Trabant/Wipeout ride, possibly themed to Disney/Pixar/Marvel characters, with the outside themed to classic pleasure pier architecture), a shop & a quick food stand, and you put a gate to the Paradise Pier Hotel at the other end.
I also think they should think about putting the Paradise Pier parking into a parking structure and expanding the current Paradise Pier Hotel into a multi-tower themed resort, but that's probably for another post.
I think they should put something like supreme scream at knotts. That rides fun. Or a beauty and the beast ride since disneyworld got beauty and the beast land.
Maybe an AP Exclusive lounge. ;)
It's a contentious subject, I know. As an asthmatic I do try to avoid the smoking areas, but it can be tough - that one right by the Matterhorn isn't exactly out of the way. The one on the Maliboomer site on the other hand is back in a corner, and it's easy enough to stay away from that one.
Re: The Maliboomer. Something should go there, but none of the things mentioned so far really work for me. Villains Funhouse? Why not have the villains in rides from their respective franchises? (I mean, they already team up in Fantasmic!). Ratatouille ride? I'd love it (it's my favorite Pixar movie) but Paradise Pier seems like the last place gourmet French chef Remy would be. (It seems more like the kind of place his non-Disney "cousin" Templeton would enjoy... "A fair is a veritable smorgasbord, orgasbord, orgasbord, after the gates are shut..." ;) )
BTW, Iger was once quoted as saying "Ratatouille is not a franchise" (i.e., not merchandisable by the people who can't figure out how to merchandise anything slightly nontraditional) so I think a ride in the U.S. is unlikely, since all rides now seem to have to double as advertisements for merch.
Space for transition between topics...
Re: Smoking area. My uncle died of lung cancer because he smoked, but I still have no problem with the smoking areas in Disneyland. Personally, they have never bothered me. I could see if it was in an enclosed space, like the "smoking areas" in restaurants from the olden days, but this is out in the open air.
There's a commercial out right now that is shown in EVERY commercial break on EVERY channel where I live. It shows a woman smoking alone on her patio at night. The puff of smoke wafts up through an open window into another apartment, through the livingroom, and into a nursery, where it morphs into a SKULL-FACED POLTERGEIST and menaces a baby. By the way, this appears to be in an urban area, with smog, car exhaust, etc., but yeah, the smoke from that one cigarette is the only dangerous thing in the air. I used to like anti-smoking PSAs that were about why smoking is bad for you, and why you should choose not to do it. They were clever and convincing. But this is just fear-mongering and making an excuse to harass people, which is not going to make them stop smoking. (This is directed more at that ad than anyone in this thread. I'm sorry but aside from the fact I don't like it, they just show it too darn often!)