I wouldnt mind a second GP in the US, specially in NJ. I have tons of family and friends to crash w/ but I would have a major problem w/ another boring street circuit
Valencia and Singapore are extremely boring tracks, not only to watch but to race also. Singapore has been borderline acceptable cause of all the shit that has happened in the past, similar w/ Valencia. Unless something crazy happens, we forget those races even took place.
You cant compare these to Monaco though. Monaco has so much history its ridiculous and the track is amazing to drive, its one of my fav tracks in F1 2010/11. Maybe because I grew up watching Senna tear it up through there but its one of my fav tracks.
If they can pull off an exciting street circuit, then by all means