I personally would have preferred Roskam stick around in the house a bit longer, as he just got re-elected to a second term and isn't a GOP powerhouse yet, but his win against Rahm Emanuel's handpicked "war hero" candidate and top priority race in the Dem tidal wave of 2006 is impressive (I volunteered during that campaign).
My first preference, of course, would be Peter Fitzgerald come out of retirement and make an effort to get his old seat back (of course he now lives in Virginia so he'd have to re-establish residency in Illinois quickly), since he's been proven right about the combine, and most of the George Ryan Republicans who stabbed him in the back the first time around are gone now (Topinka, LaHood, etc., though Andy McKenna is sadly still state party chairman after leading us through the two worst defeats in history)
If not Fitzgerald, then Roskam or Shimkus would make a strong candidate in a special election. Mike Ditka jumping in as a "celeb candidate" might work too, though 2004 was really the best option for that.
I think Roskam’s political future lies on Springfield. I would like to see him reform state government. Given IL’s Obama worship, Republicans are non-starters for a Senate race. However, IL voters might be more opened minded to elect Republicans for state offices. Madigan, jones, and Blago have done splendid jobs in fiscal mismanagement. Last year around this time, it looked liked the Chicago CTA was going to shut down.
For the Senate seat, let’s give Oberweis another chance to make a fool of himself.