It seems there are 2 points of entry, one on west pier and one at the bottom of Manhatten. Do they sail exactly the same parts wherever you take it from - e.g. the 2 hour semi-cruise, will it see same parts?
Also, which would you recommend, we wondered about the 3 hour dinner cruise, is the food good and do you need to dress more formally for this? Which port would you go from West or South, and why?

www.circleline.com

Whichever pier is more convenient, that is the one I'd choose.

The Circle Line website has maps of the routes from each departure pier.

Our favorite is the Harbor Lights cruise that leaves from 42nd street. We have a nice dinner afterward, preferring to spend the entire cruise gazing at the awesome scenery all along the way.

We took the Harbor Lights and would also recommend that.... seeing the sun set and the lights go on in NYC was quite awesome! Although two days later and the lights wouldn't have gone on.... as the blackout hit

You'll be better off separating the cruise and the dinner into two separate activities. The food on dinner cruises is mediocre to average at best. And, it's expensive.

We did the 3 hour daytime cruise. While we enjoyed about 2 hr of it, it was a bit long, with relatively little to see or hear about the last 1/3 of the trip. Our narrator/Tourguide was very good, and they didn't do the usual repeated sales pitches for the snack bar, as many other trips I've made have.

Thanks everyone, we have decided on the sunset harbour lights cruise for 2 hours. Would Saturady or Sunday be best night? Also, how do we get back to T. Square without walking - heard taxis are few and far between at the Pier - is there some dodgy areas around there at night?

The 42nd Street crosstown bus stops right at the Circle Line Pier, I believe.

You can take the M42 bus, but it's also perfectly safe to walk down 42nd.

Agree that it's safe to walk 42nd Street back to Times Square. The #42 bus goes east on 42nd, but there's also the #50 which starts right across from the Circle Line terminal and goes east on 50th, so you can select either based upon your destination.

Be sure to dress warmly this time of year because out on the water it gets very chilly! Slacks are fine in NYC.

DOes anyone know what the rest room situation is at the pier waiting for the cruise to begin and aboard the ship?

These are enormous boats - naturally there are a number of restrooms aboard. Don;t know about the pier/office - but imagine there must be something for an emergency.