I guess its a matter of individual aircraft, weights and velocities and viewing angle. Although larger aircraft seam to spark quite freely, finding a good video of a light aircraft sparking is quite hard.
This light plane has quiet a healthy spark at around 16sec of the clip, seen from another angle this may have gone un-noticed.
(sorry -disable in embeded- need to open it in a new window or tab!)
Something like a Spitfire or a mustang would be twice as heavy as this light plane and the Mustang has large magnesium alloy casting for attachment of the undercarrage.
Unfortunately owners of old war birds tend to be quite gentle with them when their doing forced landings and perfer to land on the grass at the side of the strip (very considerate!) so like I said theres not many videos around of them landing on concrete.
No matter what, like Alpha said I would not like hollywood style fires and effects. Keep it realistic!