Revelations: Not Necessarily Star Wars
"There's a reason why most modern TV serieses these days have two-part pilots; because one hour isn't enough to introduce a situation and develop characters." I know this is horribly nitpicky, but this is really not true. Even if we disregard comedies (though you said "TV series" not "TV dramas"), most shows DO have a one-hour pilot from what I can tell. The ones that do get a two-hour pilot are in the minority and tend to only be the shows the network is really pinning their hopes on.