Having been up to NYC a couple times, I seen much of the cities sights. Now, i want to see NYC a little more in depth. Instead of spending the night, I prefer to come up to NY on daytrips from Baltimore, MD. Stuff i still want to do is:
Going up in the Empire State Building
Seeing the Sites in Central Park
American Museum of Natural History
Statue of Liberty and Ellis Island

How would i split these activities into 2 seperate trips? The bus i take drops me off near Times Square. So, i would take the subway down to the Statue of Liberty and/or American Museum of Natural History.

I'd split up the four destinations this way:
1. The Empire State Building and the Statue of Liberty/Ellis Island.
2. Central Park and the American Museum of Natural History.
As for the first one, start with the SOL and Ellis Island and finish up with the Empire State Building. However, bear in mind that most of us regulars on the forum would recommend the Top of the Rock over the ESB.
The museum and Central Park are natural to go together geographically.
But why would you prefer to do these activities as two separate day trips from Baltimore. That seems to be a terrible waste of time taking a bus each time.

Could do that. Probably would be a good idea to get tickets for the Empire State Building to fit it in with the Statue of Liberty. What is the deal with the Statue of Liberty and going up in the Crown? Should I bother with this or just get the normal tickets that go inside the statue to the Pedestal?

BTW, I ve done Top of the Rock. I want to go up in the Empire State Building because i haven't been before.

The Statue of Liberty requires you to buy tickets in advance - and they sell out far in advance. From the time you arrive at South Ferry it will take about 5 hours to get to the ferry, go through security line (45 minutes or so), get to Liberty Island, see the Statue and take the ferry to Ellis Island and back of South ferry. (the later you get to the ferry the longer the trip would take.) Trying to do the ESB in the same trip can be a problem - again, since the lines are very long.

You can spend a couple of hours at Nat'l Hist (go to the web site in advance to pick out what you want to see). For Central Park go to the web site of the Central Park Conservancy to pick out which things you want to see - there's no way you can see all of either, never mind both, in one brief day.

I have about 7-8 hours in New York when i take the bus up. Surely, yes i can't see everything in the museum and in central park in one visit. But, if i bought tickets online, should the Empire State Building still take a long time?
Thanks-

The problem is that you don't know how long it will take for the visit to the ESB. So, from that point of view, it would seem that you should go there first. However, that means going to the SOL and Ellis Island later when the lines are much longer there cutting down your visiting time there.

Even though it makes more sense to split the attractions according to the areas, since you are arriving and leaving from Times Square area it might make more sense to do the Empire State Building early one day and the SOL etc. early the other day which would leave you to fit the museum and Central Park into the rest of your days depending on how much time remains (especially if you are comfortable with the subway).

We bought tickets online for the ESB and would definitely recommend doing that (I don't think we had to buy them for a certain day), but it doesn't cut down the wait in line substantially for your predictament. We still had to wait over an hour (there was a sign outside telling how long the wait would probably be and we found it accurate at that time -- you could also call a number to see how long the wait is which may work for you if your tickets aren't dated and you find you have time to go there after you leave the SOL trip).

I think maj's suggestion about doing the ESP early one day and the SOL/Ellis Island jaunt early the other day makes sense, even though the matching of the four destinations isn't the best.

If you're thorough, am thinking you could easily spend a day trip each on Statue of Liberty/Ellis Island (slow logistics, get tickets and reservations ahead), Empire State Building (long lines), Central Park (large and sprawling), and American Museum of Natural History (huge), perhaps with additional smaller add-ons (there are no shortage of these).

With day trips, keep in mind that the bus or train in likely will arrive mid- to late morning and the last one out likely leaves in late afternoon or early evening. If they're on time, count on ca. 6-7 hours of sightseeing and in-Manhattan travel time at most.

Yes, the ESB has a

1) ticket buyer's line
2) line waiting to get on the first elevator
3) line waiting to switch to the second elevator to go to the top

Depending on day and time this process can take and hour - or it can take 3.

What if you already have tickets? Does that mean you skip the ticket buyer's line?