Bait and switches are almost never a good idea.

When ABC presented last week’s “Grey’s” Anatomy” and “”Private Practice” as a crossover event, the only thing resembling a crossover was a frazzled Addison Montgomery-Shepherd (Kate Walsh) calling her ex-husband Derrick Shepherd (Patrick Dempsey), asking him to perform surgery on her cancer-stricken brother.

The hype resulted in a jolt for both shows. “Grey’s” attracted up to 15 million viewers; while “Private Practice” drew 13 million as one of its largest audiences ever. The network gave little away last week while saving the really big stuff for tonight’s two hour event, beginning at 9 p.m. on ABC.

“Grey’s” has been hard to watch this year, with the asinine storyline of Izzie Stevens (Katherine Heigl) seeing the ghost of Denny and George O’Malley (T.R. Knight) getting very little screen time.

The decision to fire Brooke Smith, who played Erica Hahn, and the release of Melissa George, who played Sadie Harris, also made the show less interesting.

The stuff that has worked is the fantastic Mark Sloan/Lexie Grey romance, which has slowly and realistically developed as well as the onscreen dynamic between newcomer Owen Hunt (Kevin McKidd) and Cristina Yang (Sandra Oh).

Bringing beloved character Addison back into the fold with Naomi Bennett (Audra McDonald) and Sam Bennett (Taye Diggs) from “Private Practice” will allow people to see how fun these characters are and maybe decide to continue giving the spinoff a chance once the crossover ends.

“Grey’s” missed the boat with Addison by not pairing her with Alex Karev (Justin Chambers) because the two had great chemistry.

It remains interesting to me that two years into the spinoff, the writers have yet to find a good love interest for Addison. The best part of the spinoff is the chemistry between Violet Turner (Amy Brenneman) and Cooper Freedman (Paul Adelstein).

Cooper’s work as a pediatrician is so believable and fun to watch, as is his devotion to his best friend Violet. She has been tortured by a bunch of bad romantic choices, and her current dilemma finds her pregnant with a child who was fathered by one of two guys she works with.

Cooper, being the friend he is, has moved in to help Violet while she struggles alone with her pregnancy. Hopefully the story tonight puts some focus on these two so the “Grey’s”-only fans can see what they are missing.

My hope for the remainder of the season for both shows is that Meredith Grey (Ellen Pompeo) and Derek finally get engaged, as everyone knows about the upcoming proposal except poor Meredith.

Knight deserves a lot more screen time. What Shonda Rhimes has done by omitting him from the main stories this season is an embarrassment.

Denny’s ghost should never appear to Izzie again, as the entire storyline drags down each episode it appears in and is a gross underutilization of Heigl’s talent.

Mark and Lexie should get highlighted even more than they already are.

Hopefully Addison gets a love interest that is her equal, unlike the boring cop they paired her with for a year and a half. Finally, it would be awesome to see Cooper and Violet get romantically involved.

The crossover will definitely continue to spike interest in both popular ABC dramas, and it is up to Rhimes and crew to provide satisfying arcs to conclude the season.